Docs: Replace Recommonmark with MyST Parser

Recommonmark has been deprecated since 2021 [1] and the last release was
over 3 years ago [2]. As per their announcement, Markedly Structured
Text (MyST) Parser [3] is the recommended replacement.

For the most part, the existing documentation is compatible with MyST,
as both parsers are built around the CommonMark flavor of Markdown. The
main difference that affects coreboot is how the Sphinx toctree is
generated. Recommonmark has a feature called auto_toc_tree, which
converts single level lists of references into a toctree:

* [Part 1: Starting from scratch](part1.md)
* [Part 2: Submitting a patch to coreboot.org](part2.md)
* [Part 3: Writing unit tests](part3.md)
* [Managing local additions](managing_local_additions.md)
* [Flashing firmware](flashing_firmware/index.md)

MyST Parser does not provide a replacement for this feature, meaning the
toctree must be defined manually. This is done using MyST's syntax for
Sphinx directives:

```{toctree}
:maxdepth: 1

Part 1: Starting from scratch <part1.md>
Part 2: Submitting a patch to coreboot.org <part2.md>
Part 3: Writing unit tests <part3.md>
Managing local additions <managing_local_additions.md>
Flashing firmware <flashing_firmware/index.md>
```

Internally, auto_toc_tree essentially converts lists of references into
the Sphinx toctree structure that the MyST syntax above more directly
represents.

The toctrees were converted to the MyST syntax using the following
command and Python script:

`find ./ -iname "*.md" | xargs -n 1 python conv_toctree.py`

```
import re
import sys

in_list = False
f = open(sys.argv[1])
lines = f.readlines()
f.close()

with open(sys.argv[1], "w") as f:
    for line in lines:
        match = re.match(r"^[-*+] \[(.*)\]\((.*)\)$", line)
        if match is not None:
            if not in_list:
                in_list = True
                f.write("```{toctree}\n")
                f.write(":maxdepth: 1\n\n")
            f.write(match.group(1) + " <" + match.group(2) + ">\n")
        else:
            if in_list:
                f.write("```\n")
            f.write(line)
            in_list = False

    if in_list:
        f.write("```\n")
```

While this does add a little more work for creating the toctree, this
does give more control over exactly what goes into the toctree. For
instance, lists of links to external resources currently end up in the
toctree, but we may want to limit it to pages within coreboot.

This change does break rendering and navigation of the documentation in
applications that can render Markdown, such as Okular, Gitiles, or the
GitHub mirror. Assuming the docs are mainly intended to be viewed after
being rendered to doc.coreboot.org, this is probably not an issue in
practice.

Another difference is that MyST natively supports Markdown tables,
whereas with Recommonmark, tables had to be written in embedded rST [4].
However, MyST also supports embedded rST, so the existing tables can be
easily converted as the syntax is nearly identical.

These were converted using
`find ./ -iname "*.md" | xargs -n 1 sed -i "s/eval_rst/{eval-rst}/"`

Makefile.sphinx and conf.py were regenerated from scratch by running
`sphinx-quickstart` using the updated version of Sphinx, which removes a
lot of old commented out boilerplate. Any relevant changes coreboot had
made on top of the previous autogenerated versions of these files were
ported over to the newly generated file.

From some initial testing the generated webpages appear and function
identically to the existing documentation built with Recommonmark.

TEST: `make -C util/docker docker-build-docs` builds the documentation
successfully and the generated output renders properly when viewed in
a web browser.

[1] https://github.com/readthedocs/recommonmark/issues/221
[2] https://pypi.org/project/recommonmark/
[3] https://myst-parser.readthedocs.io/en/latest/
[4] https://doc.coreboot.org/getting_started/writing_documentation.html

Change-Id: I0837c1722fa56d25c9441ea218e943d8f3d9b804
Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73158
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 20 insertions, 12 deletions

diff --git a/Documentation/getting_started/build_system.md b/Documentation/getting_started/build_system.md
index 35ed187989..4c91f436ec 100644
--- a/Documentation/getting_started/build_system.md
+++ b/Documentation/getting_started/build_system.md
@@ -75,7 +75,7 @@ $(call add_intermediate, add_mrc_data)
 
 Note that the second line must start with a tab, not spaces.
 
-```eval_rst
+```{eval-rst}
 See also :doc:`../tutorial/managing_local_additions`.
 ```
 
diff --git a/Documentation/getting_started/gpio.md b/Documentation/getting_started/gpio.md
index fd0267aac5..4baaa7a5f5 100644
--- a/Documentation/getting_started/gpio.md
+++ b/Documentation/getting_started/gpio.md
@@ -167,7 +167,7 @@ could cause catastrophic failures, up to and including your mainboard!
 As per Intel Platform Controller Hub (PCH) EDS since Skylake, a GPIO PAD register
 supports four different types of GPIO reset as:
 
-```eval_rst
+```{eval-rst}
 +------------------------+----------------+-------------+-------------+
 |                        |                |         PAD Reset ?       |
 + PAD Reset Config       + Platform Reset +-------------+-------------+
diff --git a/Documentation/getting_started/index.md b/Documentation/getting_started/index.md
index 01dbe8c87a..7180c9615a 100644
--- a/Documentation/getting_started/index.md
+++ b/Documentation/getting_started/index.md
@@ -1,10 +1,14 @@
 # Getting Started
 
-* [coreboot architecture](architecture.md)
-* [Build System](build_system.md)
-* [Submodules](submodules.md)
-* [Kconfig](kconfig.md)
-* [Writing Documentation](writing_documentation.md)
-* [Setting up GPIOs](gpio.md)
-* [Adding devices to a device tree](devicetree.md)
-* [Frequently Asked Questions](faq.md)
+```{toctree}
+:maxdepth: 1
+
+coreboot architecture <architecture.md>
+Build System <build_system.md>
+Submodules <submodules.md>
+Kconfig <kconfig.md>
+Writing Documentation <writing_documentation.md>
+Setting up GPIOs <gpio.md>
+Adding devices to a device tree <devicetree.md>
+Frequently Asked Questions <faq.md>
+```
diff --git a/Documentation/getting_started/kconfig.md b/Documentation/getting_started/kconfig.md
index ddd32762a9..c9e9b3c61a 100644
--- a/Documentation/getting_started/kconfig.md
+++ b/Documentation/getting_started/kconfig.md
@@ -11,8 +11,12 @@ configuration front end in coreboot today.
 
 The official Kconfig source and documentation is kept at kernel.org:
 
-- [Kconfig source](https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig)
-- [Kconfig Language Documentation](https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt)
+```{toctree}
+:maxdepth: 1
+
+Kconfig source <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig>
+Kconfig Language Documentation <https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt>
+```
 
 The advantage to using Kconfig is that it allows users to easily select the
 high level features of the project to be enabled or disabled at build time.