Document conventional commits specification & tweak merging process considerations.

[SychO9]

Changes Suggested

• Officially switch to using the Conventional Commits specification, this will make changelog generation a lot easier through automation, but also makes the commit history more readable.
  • With the one custom difference being, describing the actual issue instead of the fix, when it comes to fix commits, as suggested by Daniël, this is better for the changelog.
• Tweak the merging process considerations
  • I don't believe we want regressions added to the milestone/project board.
  • I also believe we've taken the habit of creating issues in core that reference PRs in extensions that are added to the milestone. Although this won't matter once we switch to monorepo.

[SychO9]

btw, I don't believe the docs have been getting auto-updated with each new commit, the current docs don't have the latest commit changes in master.