Deploy to GitHub Pages

Added `myst_parser` to dependencies to install within build job.

Author: shorodilov

.github/workflows/deploy_pages.yml

@@ -35,7 +35,7 @@ jobs:
         uses: actions/setup-python@v2
       - name: Install dependencies
         run: |
-          pip install sphinx sphinx_rtd_theme
+          pip install sphinx sphinx_rtd_theme myst_parser
       - name: Build documents
         run: |
           LANGUAGE=en make html