Replace Netlify with Read the Docs pull request previews

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

@@ -0,0 +1,22 @@
+# .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/**"
+
+permissions:
+  pull-requests: write
+
+jobs:
+  documentation-links:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: readthedocs/actions/preview@v1
+        with:
+          project-slug: "plone6"
+          single-version: "true"

.readthedocs.yaml

@@ -0,0 +1,25 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the OS, Python version and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+  commands:
+    # Cancel building pull requests when there aren't changes in the docs directory or YAML file.
+    # You can add any other files or directories that you'd like here as well,
+    # like your docs requirements file, or other files that will change your docs 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/ .readthedocs.yaml requirements.txt;
+      then
+        exit 183;
+      fi
+    - make rtd-pr-preview

Makefile

@@ -208,10 +208,10 @@ test: clean linkcheckbroken  ## Clean docs build, then run linkcheckbroken
 .PHONY: deploy
 deploy: clean html
 
-.PHONY: netlify
-netlify:
+.PHONY: rtd-pr-preview
+rtd-pr-preview:  ## Build pull request preview on Read the Docs
 	pip install -r requirements.txt
-	cd $(DOCS_DIR) && sphinx-build -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	cd $(DOCS_DIR) && sphinx-build -b html $(ALLSPHINXOPTS) ${READTHEDOCS_OUTPUT}/html/
 
 .PHONY: all
 all: clean vale linkcheck html ## Run checks and build html