When getting started, making small changes and then checking to
make sure they worked is best. But that makes for a lot of uploads back
to GitHub and waiting around
If you are editing HTML directly, then you can just open the file
locally to see the changes
If using a templating engine like Jekyll though, you would need
to have Jekyll installed locally to build the site. Which is not
trivial.
Docker to the rescue! From your local website folder:
docker run -it --rm -v .:/srv/jekyll -p 4000:4000 \
jekyll/jekyll jekyll serve --watch --force_polling \
--verbose --livereload --host 0.0.0.0