Add build docs workflow

.github/workflows/docs.yml

@@ -0,0 +1,21 @@
+on: [push, pull_request]
+name: build-docs
+jobs:
+  tests:
+    runs-on: ubuntu-20.04
+    name: Build docs
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.11
+          architecture: x64
+      - name: Update tools
+        run: pip install --upgrade pip setuptools wheel
+      - name: Install sphinx
+        run: pip install sphinx
+      - name: Install package
+        run: pip install -e .
+      - name: Build docs
+        run: cd docs && make html

docs/Makefile

@@ -2,7 +2,7 @@
 #
 
 # You can set these variables from the command line.
-SPHINXOPTS    =
+SPHINXOPTS    = -W
 SPHINXBUILD   = sphinx-build
 SOURCEDIR     = .
 BUILDDIR      = _build

docs/conf.py

@@ -66,7 +66,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.