Make docs/ a pure Markdown content directory (#4583)

Remove the Read the Docs and Sphinx configuration (.readthedocs.yaml,
conf.py, requirements.txt, Makefile, theme templates and static assets)
along with the docs pip ecosystem in dependabot and the .readthedocs.yaml
entries in workflow paths-ignore lists.

Port the three remaining reStructuredText files to Markdown:
index.rst becomes index.md, and language-support and using-go-and-pgx
are now GitHub-flavored Markdown using alert-style admonitions. Links
that pointed at .rst files now point at their .md replacements.

Add docs/toc.yaml, which declares the navigation order previously held
in index.rst's toctree directives: every page appears exactly once,
either in a titled section or in the unlisted set. This file is the
contract a docs site consumer reads, and a future Go-based linter will
enforce it.


Claude-Session: https://claude.ai/code/session_013XDcHxZk9UzfzMLayG66Zq

Co-authored-by: Claude <noreply@anthropic.com>

Author: kyleconroy

.github/dependabot.yml

@@ -17,18 +17,4 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
-  - package-ecosystem: "pip"
-    directory: "/docs"
-    schedule:
-      interval: "daily"
-    ignore:
-      # sphinx-rtd-theme does not support the latest versions of docutils and
-      # sphinx
-      - dependency-name: "docutils"
-      - dependency-name: "sphinx"
-    groups:
-      production-dependencies:
-        dependency-type: "production"
-      development-dependencies:
-        dependency-type: "development"
 

.github/workflows/buf.yml

@@ -3,7 +3,6 @@ on:
   pull_request:
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
 jobs:
   build:
     runs-on: ubuntu-latest

.github/workflows/ci-kotlin.yml

@@ -5,11 +5,9 @@ on:
       - main
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
   pull_request:
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
 jobs:
   build:
     if: false

.github/workflows/ci-python.yml

@@ -5,11 +5,9 @@ on:
       - main
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
   pull_request:
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
 jobs:
   build:
     if: false

.github/workflows/ci-typescript.yml

@@ -5,11 +5,9 @@ on:
       - main
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
   pull_request:
     paths-ignore:
       - 'docs/**'
-      - '.readthedocs.yaml'
 jobs:
   build:
     if: false