docs: reorg for nested sections (#835)

* docs: reorg for nested sections

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* style: pre-commit fixes

---------

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: henryiii

docs/guides/gha_basic.md

@@ -1,8 +1,8 @@
 ---
-short_title: GitHub Actions introduction
+short_title: Introduction
 ---
 
-# GitHub Actions: Intro
+# GitHub Actions: Introduction
 
 {rr}`GH100` The recommended CI for scientific Python projects is GitHub
 Actions (GHA), although its predecessor Azure is also in heavy usage, and other

docs/guides/gha_pure.md

@@ -1,8 +1,8 @@
 ---
-short_title: GitHub Actions for pure Python wheels
+short_title: Pure Python projects
 ---
 
-# GitHub Actions: Pure Python wheels
+# GitHub Actions: Pure Python projects
 
 We will cover binary wheels [on the next page][], but if you do not have a
 compiled extension, this is called a universal (pure Python) package, and the

docs/guides/gha_wheels.md

@@ -1,8 +1,8 @@
 ---
-short_title: GitHub Actions for Binary Wheels
+short_title: Compiled projects
 ---
 
-# GitHub Actions: Binary wheels
+# GitHub Actions: Compiled projects
 
 Building binary wheels is a bit more involved, but can still be done effectively
 with GHA. This document will introduce [cibuildwheel][] for use in your project.

docs/guides/packaging_compiled.md

@@ -1,4 +1,4 @@
-# Packaging Compiled Projects
+# Compiled packaging
 
 <!-- [[[cog
 from cog_helpers import code_fence, render_cookie, TOMLMatcher

docs/myst.yml

@@ -22,14 +22,18 @@ project:
         - file: guides/pytest.md
         - file: guides/coverage.md
         - file: guides/docs.md
-        - file: guides/packaging_simple.md
-        - file: guides/packaging_compiled.md
-        - file: guides/packaging_classic.md
+        - title: Packaging
+          children:
+            - file: guides/packaging_simple.md
+            - file: guides/packaging_compiled.md
+            - file: guides/packaging_classic.md
         - file: guides/style.md
         - file: guides/typing.md
-        - file: guides/gha_basic.md
-        - file: guides/gha_pure.md
-        - file: guides/gha_wheels.md
+        - title: GitHub Actions
+          children:
+            - file: guides/gha_basic.md
+            - file: guides/gha_pure.md
+            - file: guides/gha_wheels.md
         - file: guides/security.md
         - file: guides/tasks.md
     - file: principles/index.md