Updated rules for submitting pull requests




Today i have updated rules for submitting pull requests.

From no one you should just push your feature branch to the upstream repository without merging with develop/release branch.

Only maintainer has rights to merge changes to develop/release branch.

This change helps maintainers to easy make additional fixes to a pull request and at the same time keep the repository history more clean.

@Bojan and @Valentina_Zhuravska don’t miss this change!

Link to updated document Hacking:Making pull requests - Seamly2D.