Update Mapbase contribution guidelines and PR template#421

Blixibon wants to merge 1 commit intomapbase-source:developmapbase-source/source-sdk-2013:developfrom

Blixibon:mapbase/feature/v8.0-contribution-guidelinesBlixibon/source-sdk-2013:mapbase/feature/v8.0-contribution-guidelinesCopy head branch name to clipboard