Add ReadTheDocs build config for PR previews (#9)

* Add RTD build config

* Add RTD link to PR descriptions

Author: mfisher87

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

@@ -0,0 +1,24 @@
+# The ReadTheDocs preview link is "hidden" within the GitHub "Checks"
+# interface. For users who don't know this, finding the preview link may be
+# very difficult or frustrating. This workflow makes the link more
+# findable by updating PR descriptions to include it.
+name: 'Add ReadTheDocs preview link to PR description'
+
+on:
+  pull_request_target:
+    types:
+      - 'opened'
+
+permissions:
+  pull-requests: 'write'
+
+jobs:
+  autolink-rtd-previews:
+    runs-on: 'ubuntu-latest'
+    steps:
+      - uses: 'readthedocs/actions/preview@v1'
+        with:
+          project-slug: 'jupytergis'
+          message-template: |
+            :mag: Preview: {docs-pr-index-url}
+            This Pull Request preview is provided by ReadTheDocs. Our production website, however, is currently deployed with GitHub Pages.

.readthedocs.yaml

@@ -0,0 +1,21 @@
+# For this project, we use ReadTheDocs only for Pull Request previews. GitHub
+# pages currently hosts the actual website.
+version: 2
+
+
+build:
+  os: "ubuntu-lts-latest"
+
+  commands:
+    # Download: https://quarto.org/docs/download/tarball.html
+    - "wget https://github.com/quarto-dev/quarto-cli/releases/download/v1.6.40/quarto-1.6.40-linux-amd64.tar.gz"
+
+    # Install
+    - "mkdir --parents ~/opt/quarto ~/bin"
+    - "tar -C ~/opt/quarto -xvzf quarto*.tar.gz --strip-components 1"
+    - "ln -s ~/opt/quarto/bin/quarto ~/bin/quarto"
+
+    # Render
+    - "cd doc && ~/bin/quarto render"
+    - "mkdir --parents $READTHEDOCS_OUTPUT/html/"
+    - "mv doc/_site/* $READTHEDOCS_OUTPUT/html/."