Build docs and upload to gh-pages (#1232)

For #889

docs/CMakeLists.txt

@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.16.3)
+project(docs)
+
+include(${CMAKE_CURRENT_SOURCE_DIR}/../CMake/ClioVersion.cmake)
+
+# Generate `docs` target for doxygen documentation
+# Note: use `cmake --build . --target docs` from your `build` directory to generate the documentation
+include(${CMAKE_CURRENT_SOURCE_DIR}/../CMake/Docs.cmake)