Improve rtd pull request preview git diff

.github/workflows/rtd-pr-preview.yml

@@ -0,0 +1,26 @@
+# .github/workflows/rtd-pr-preview.yml
+name: readthedocs/actions
+on:
+  pull_request_target:
+    types:
+      - opened
+    # Execute this action only on PRs that touch
+    # documentation files.
+    paths:
+      - "docs/**"
+      - "*.rst"
+      - "src/icalendar/*.py"
+      - .readthedocs.yaml
+      - requirements_docs.txt
+
+permissions:
+  pull-requests: write
+
+jobs:
+  documentation-links:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: readthedocs/actions/preview@v1
+        with:
+          project-slug: "icalendar"
+          single-version: "true"

.readthedocs.yml

@@ -24,7 +24,7 @@ build:
     # If there are no changes (git diff exits with 0) we force the command to return with 183.
     # This is a special exit code on Read the Docs that will cancel the build immediately.
     - |
-      if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- docs/ src/icalender/*.py CHANGES.rst CONTRIBUTING.rst LICENSE.rst README.rst .readthedocs.yaml requirements_docs.txt;
+      if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- . docs/ src/icalendar/*.py *.rst .readthedocs.yaml requirements_docs.txt ':!src/icalendar/fuzzing' ':!src/icalendar/tests' ':!src/icalendar/timezone';
       then
         exit 183;
       fi

CHANGES.rst

@@ -66,6 +66,8 @@ New features:
 - Test compatibility with Python 3.12
 - Add function ``icalendar.use_pytz()``.
 - Add `sphinx-autobuild` for `livehtml` Makefile target.
+- Add pull request preview on Read the Docs, building only on changes to documentation-related files.
+- Add link to pull request preview builds in the pull request description only when there are changes to documentation-related files.
 - Add documentation of live HTML preview of documentation and clean up of ``install.rst``.
 
 Bug fixes: