Update contributing documentation

[DanielRosenwasser]

@RyanCavanaugh recently walked through CONTRIBUTING.md and our wiki and commented that the process is a bit old and crusty. In the interest of making things more obvious for contributors, we need to clean things up here.

[ghost]

I'm currently trying to get an overview of the project, including contribution etc.

The project-host (github) is not very helpful with this:

• 3891 issues
• 112 Issue-Labels in one(!) level
• zero functionality for "subsystems" or "components"

Any serious issue-tracker for larger projects (like typescript is) has fields for:

• Issue-Category (bug, feature, enhancement, question etc.)
• Severity (on user side)
• Priority (from team)
• most (MOST) important: Component (or Subsystem)

Don't believe this"

Test:

• Focus on the "compiler" subsystem within the typescript code.
• Get notifications ONLY for src/compiler subsystem.
• Follow Issues for the "compiler" subsystem.

=> you can't, because Github does not support this.

Why? Because the early Gihub-product-managers had "flat" thinking, and the masses were fine with it.

An excellent system needs zero documentation, because it's self-documenting.

But! A system full of weaknesses and flaws needs many documentation.

Fix those very fundamental github weaknesses, then start to write contributor-documentation.

4000 issues, 113 labels, seriously, you don't see the usability disaster here?

.