static content generator by mkdocs and hosted on readthedocs.org
link and refer to another repo as the submodule for this repo
sudo git submodule add https://github.com/liuning0820/all-posts.git docs/all-posts
# Change to the submodule directory
cd submodule_dir
# Checkout desired branch
git checkout master
# Update
git pull
# Get back to your project root
cd ..
# Now the submodules are in the state you want, so
git commit -am "Pulled down update to submodule_dir"
# Or, if you're a busy person:
git submodule foreach git pull origin master