Merge remote-tracking branch 'origin/pr/4' into feature/contributing
Add note about reporting vulns
Add an example of a good PR
Add missing period
Add more examples of good contributions
Change HTTP link to HTTPS

Doesn't redirect by default.
Add note about PR titles
Add note about the 50/72 rule
Add note about topic branches
Add note about descriptive titles in bug reports
Add a link to common coding mistakes
Update HACKING along with CONTRIBUTING.md