feat(docs): Add --open flag to build-docs.sh

Can be used to build docs and directly open them in the users default
web-browser:

	./Documentation/build-docs.sh --open

Documentation/build-docs.sh

@@ -4,3 +4,7 @@ set -e
 cd "$(dirname "$0")"
 
 sphinx-build -b html . ./output
+
+if [ "$1" = "--open" ]; then
+   xdg-open ./output/index.html
+fi