Implement upload of project documentation on readthedocs.io (#30)

* Add readthedocs.io config file

* Check docs generation in CI

.github/workflows/constraints.txt

@@ -1,2 +1,3 @@
 pip==20.2.4
 pre-commit==2.8.2
+nox==2020.8.22

.github/workflows/docs.yml

@@ -0,0 +1,18 @@
+name: Build documentation
+on: [push, pull_request]
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/[email protected]
+      - uses: actions/[email protected]
+        with:
+          python-version: "3.8"
+      - run: |
+          pip install --constraint=.github/workflows/constraints.txt pip
+          pip install --constraint=.github/workflows/constraints.txt nox
+      - run: nox --force-color --session=docs
+      - uses: actions/upload-artifact@v2
+        with:
+          name: docs
+          path: docs/_build

.readthedocs.yml

@@ -0,0 +1,8 @@
+version: 2
+sphinx:
+  configuration: docs/conf.py
+formats: all
+python:
+  version: 3.8
+  install:
+    - requirements: docs/requirements.txt