Build docs during CI

Author: rbtcollins

.github/workflows/test-docs.yaml

@@ -0,0 +1,27 @@
+name: Test build docs on PR
+
+on:
+  pull_request:
+    branches:
+      - "*"
+
+# Builds docs for both stable and master branches.
+# stable is placed in the root of the gh-pages branch, while master is placed at /devel
+
+jobs:
+  doc:
+    name: Documentation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+      - name: Install mdbook
+        run: |
+          mkdir mdbook
+          curl -Lf https://github.com/rust-lang/mdBook/releases/download/v0.4.6/mdbook-v0.4.6-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=./mdbook
+          echo "`pwd`/mdbook" >> $GITHUB_PATH
+      - name: Build book
+        run: |
+          cd doc/user-guide
+          mdbook build