attempt to create docs using sphinx in an action

.github/workflows/build-documentation.yml

@@ -0,0 +1,18 @@
+# This starter workflow is for a CMake project running on multiple platforms. There is a different starter workflow if you just want a single platform.
+# See: https://github.com/actions/starter-workflows/blob/main/ci/cmake-single-platform.yml
+name: CMake on multiple platforms
+
+on:
+  push:
+    branches: [ "trunk", "develop" ]
+
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - uses: ammaraskar/sphinx-action@master
+      with:
+        docs-folder: "docs/"
+        pre_build-command: "cmake -S . -B build -DBUILD_DOCUMENTATION=ON -DBUILD_TESTING=OFF"
+        build-command: "cmake --build build --target Sphinx-libmcfp"