modernize website build system
The current 'build system' for the documentation website involves TravisCI ( which [does not work anymore](https://blog.travis-ci.com/2021-05-07-orgshutdown) ) checking out the source, generating the website using Jekyll and then pushing the generated HTML files to the [`gh-pages`](https://github.com/ForkAwesome/Fork-Awesome/tree/gh-pages) branch which is then served at https://forkaweso.me/Fork-Awesome.

This system was inherited from the parent project Font Awesome. It was probably the ideal workflow when it was implemented 4 years ago. GitHub Pages has evolved a lot since then. It now provides a ( sand-boxed ) Jekyll environment out-of-the-box which means that it can generate the documentation website directly from source files.

But we cannot simply lift and drop the system as-is into GitHub's environment because we use a few custom plugins for the generation of the website. GitHub does not allow the use of custom plugins in its environment.

Hence, in order to use GitHub's Pages environment, we will have to 'modernize' the website source files to be compatible to work with GitHub's Pages environment.