convert esp32s2 port readme to rst

[2bndy5]

closes #3938

I chose to convert the whole file to rst syntax so that the table will render properly on github & readthedocs.
Sphinx is configured to expect either format (no need to explicitly mention the file extension).

I also verified changes render properly.

[2bndy5]

This build CI workflow takes forever. I wish there was an easy way to separate the building docs changes from the building firmware changes. My first guess would be a separate workflow for building the firmware that ignores changes to *.rst & *.md files (& the docs folder) using

on:
  push:
    paths:
      - "**/*"
      - "!**/*.md"
      - "!**/*.rst"
      - "!docs/**"
  pull_request:
    paths:
      - "**/*"
      - "!**/*.md"
      - "!**/*.rst"
      - "!docs/**"
  release:
    types: [published]
  check_suite:
    types: [rerequested]

I also find it a little weird to upload all non-released doc build artifacts. That could simply be avoided by adding

if: ${{ github.event_name == 'release'}}

for the steps following the "Test Documentation Build (<builder>)" steps.

[tannewt]

This build CI workflow takes forever. I wish there was an easy way to separate the building docs changes from the building firmware changes. My first guess would be a separate workflow for building the firmware that ignores changes to *.rst & *.md files (& the docs folder) using

We could definitely do this for pure doc changes. Many C files have docs in them as well so we'll still need the full set of tests for those changes.

I also find it a little weird to upload all non-released doc build artifacts.

We definitely want this. It allows folks to test PR artifacts without need to clone the branch locally and build.

[tannewt]

Thank you!