Add action to auto build and deploy doc

[soraxas]

This adds an auto build for the API doc, for the requirement of the JOSS guideline:

Documentation

• [ ] Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?

The generated doc is deployed at gh-pages branch, and you can host it in github page via setting your repo settings:

So that your user can directly refer to your code API

(addresses #4)

[haider8645]

Thanks, I guess that the build fails because it is trying to push to a branch here from your credentials.

[soraxas]

It runs successfully, but it won't be able to deploy to your repo (as this is my PR and doesn't have permission to push to your repo).

[soraxas]

The deployed version should looks like this: https://soraxas.github.io/ugv_nav4d (this is just my fork's gh page)