Remove GH artifact action and update workflow for gh-pages

.github/workflows/docs.yml

@@ -4,7 +4,10 @@ name: deploy-book
 on:
   push:
     branches:
-    - master
+      - master
+  pull_request:
+    branches:
+      - master
 
 # Allow the bot to push to the repository
 permissions:
@@ -23,18 +26,14 @@ jobs:
       with:
         python-version: 3.7
 
-    - name: Install dependencies
-      run: |
-        pip install -U jupyter-book
-
-
-    # Build the book
-    - name: Build the book
+    - name: Build the docs
       run: |
-        jupyter-book build .
+        pip install nox
+        nox -s docs
 
     # Push the book's HTML to github-pages
-    - name: GitHub Pages action
+    - if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+      name: GitHub Pages action
       uses: peaceiris/actions-gh-pages@v3.5.9
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}

README.md

@@ -47,6 +47,14 @@ In addition, read
 for guidance on the questions you should answer before officially submitting
 the JEP.
 
+## Docs hosting
+
+We use a GitHub action to build the documentation with Sphinx and push it to the `gh-pages` branch of the repository.
+This is then hosted at `jupyter.org/enhancement-proposals`.
+
+We use a ReadTheDocs build to automatically generate **previews** of the documentation for Pull Requests.
+However this is not the publicly-hosted version of the documentation, it is just for PRs.
+
 ## Build the enhancement proposal docs
 
 The Enhancement Proposal documentation is structured as a [Sphinx documentation site](https://www.sphinx-doc.org/) that uses a them and configuration inspired by [Jupyter Book](https://jupyterbook.org).