Minor fixes on documentation pages

[pabluk]

This PR just fix some minor typos/spelling errors I found when I was reading the documentation site.

At first, I just wanted to try the Github Actions env vars, but after doing a copy/paste on my terminal I found out that there was a typo on the GITHUB_WORKFLOW variable name, so to avoid just creating a pull request with only a new byte on it I also run aspell check on all the *.rst files under docs/ and I checked all the URLs.

I didn't find any open issues related to this but I can open a new issue if you want.

Please feel free to request any changes or drop this PR if it's not relevant. Thanks

[ssbarnea]

@pabluk Thanks! For obvious fixes like this we even prefer to just see a PR and bypass the issue creation.

In fact our project is using codespell inside .pre-commit-config.yaml which is catching some typing errors. I am not sure if aspell has support for pre-commit. If you find one way to add it to our pre-commit config, it could be useful in the future.