Create an errata doc for general coding practice

[JoshuaKGoldberg]

It should mention requirements for all code vs preferences going forward.

Sample requirements - All new code should follow these, and all old code modified.

• Interface vs class usage
• types still have I prefix
• jsdoc usage
  • @param name description...

Sample preferences - All new code should follow these. Old code being modified is a plus, but not necessary.

• Lambas over .bind
• Interfaces sort by required vs optional, then alphabetically (unless only a few members and another order takes logical precedent, such as top-right-bottom-left)
• "index": <value> vs index: value in objects
  • (the ideal should be to use quotes if it's an [i: string], and no quotes if it's a known member)