Convert build/docs/*.rst (top-level and mozbuild/) to MyST-flavored
Markdown.
- Keep build/docs/mozbuild-symbols.rst as RST. The mozbuildsymbols
custom directive emits nodes that confuse autosectionlabel when
wrapped in a MyST eval-rst block.
- Keep build/docs/supported-configurations.rst as RST so that
docs/contributing/build/supported.md can continue to use the MyST
{include} directive on the original source.
- Refresh allowed-warnings globs to match the .md filenames for
code-quality, contributing, crash-reporting, gtest, jsloader, js,
overview, setup, and js/build.
Differential Revision: https://phabricator.services.mozilla.com/D304226
Sylvestre Ledru
df0583fb15