infrastructure: provide instructions how to solve gitlint warnings

[AlexanderLanin]

Users who are trying to create a commit are typically not aware of how to fix a gitlint warning.
For example score mandates a "<lower_case_prefix>:" for commits and a commit body.
The warning should mention how to change the commit message and overwrite the old commit (force push).

Bonus: consider checking such rules pre-commit!

example: #206