Add an HTML documentation generator based on the .md files

[anovikov-el]

Description

Currently, the RMK documentation is stored in https://github.com/edenlabllc/rmk/tree/develop/docs

An advanced web documentation generator might be needed in future to structure the documentation and generate a static HTML web site.

Example of the solutions: https://pages.github.com/

Agree to the Code of Conduct

• [X] I agree to follow this project's Code of Conduct

[anovikov-el]

@apanasiuk-el After the investigation of available solutions, it became clear that:

• the repository should be the same: it will be much easier to manage and version the documentation
• the engine should be Material for MkDocs: the solution is already used in popular OSS projects like GoReleaser, K3D, as well as by Edenlab's Kodjin
• visual themes, HTML generation settings, CI/CD configurations should be standard and commonly used
• a static domain can be added in future similar to https://docs.kodjin.com/