Preparation or improvement of the guide for implementation of `GitHubInterface` class that provides simple interface for `PyGitHub` library (issue #868 related)

[bogumilchilinski]

The goal is to prepare or improve a guide or report that is generated by the following code:

from dynpy.utilities.documents.document import GithubSynchroGuide
GithubSynchroGuide();

[amvdek]

Additional reporting component has been implemented that presents usage of the GitHubInterface class (#714 ).

The code was checked with the following call:

from dynpy.utilities.documents.document import GithubSynchroGuide
GithubSynchroGuide();