GC-45: Update copyright information:

- Changes to code base were previously done in 2020 as well (based on
git history).

GC-45: Fix/update documentation building:

- Updated Sphinx requirement to latest version compatible with Python
3.8.
- Updated Sphinx configuration file to match with configuration
generated by the updated version.
- Updated copyright notices in changed files.

GC-2: Adding initial documentation skeleton with some basic information about the project:

- Added basic documentation describing the project.
- Updated gitignore file to ensure documentation build artifacts stay
out of the repository.
- README file placed at top directory for convenient access.