CONTRIBUTING.md ToC out of date

[fyliu]

Overview

As an active project, we need to keep the onboarding documentation updated so that newcomers have an easier time getting through the initial tasks. For this issue, we need to update the CONTRIBUTING.md table of contents, or remove it and tell people to use the GitHub auto-generated outline instead.

Action Items

• [Option 1] Remove the ToC and use the auto-outline
  • Remove the ToC
  • Add instruction on how to toggle the outline
• [Option 2] Update the ToC
  • Fix indents
  • Fix the order of items
  • Add missing item
  • Fix bad link and verify other links

Resources/Instructions

The image shows several things:

1. There's a button in the upper-right to toggle the auto-outline, which is the column to the right.
2. The manually-maintained ToC in the document now contains some errors:
   1. Some items should have reduced indentation (see short arrowed lines on the left)
   2. A couple items have swapped positions (see dotted line)
   3. One link is bad (see double arrow dashed line)
   4. One item is missing (see dotted single arrow line)