fae9e84cbb doc: Add GitHub pr template (MarcoFalke)
Pull request description:
Bitcoin Core has a very thorough review process and even the most trivial change needs to pass a lot of eyes and requires non-zero or even substantial time effort to review. There is a huge lack of active reviewers on the project, so patches often sit for a long time.
Authors should provide clear motivation for patches and explain how it improves Bitcoin Core user experience or Bitcoin Core developer experience significantly.
Tree-SHA512: 83b379d75934089f13ba173e6ec847845f954f10f83e406ef9722836aa093170c612b4214f22cd5939d59f66a50f5d0e52aa0059423e8e7261bb176f1c546a08
