docs: versionchanged for kwargs argument

* Adds `versionchanged` for kwargs argument.  (PR #20)

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
docs: documentation of missing methods

* Adds documentation for missing methods, making `run-tests.sh` to pass
  again.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
Co-authored-by: Jiri Kuncar <jiri.kuncar@cern.ch>
setup: richer `MANIFEST.in`

* Enriches `MANIFEST.in` as per recommendations from `check-manifest`.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
Flask-Menu v0.2.0

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Tibor Simko <tibor.simko@cern.ch>