Refine ENSRainbow Docs

[djstrong]

Increase use of "DRY" across ENSRainbow docs and comments

DRY: "don't repeat yourself"

We don't want to go too crazy with this. There's definitely an ideal balance and some level repeating the documentation of an idea in multiple places is appropriate. However we currently are out of balance on this idea. Ideas are duplicated in too many places which makes it difficult to maintain and keep up to date.

Goals here include:

• Where appropriate, transfer the "canonical" home of where an idea is documented into the ENSNode docs website. In other words if we have a bunch of docs about an idea in our code, it's generally better to transfer the docs of that idea into the ENSNode docs website and then in our code make a comment with a hyperlink to the relevant page / anchor link on our docs site with additional info.
• Refine the organization of ideas on our ENSNode docs website to reduce the cases of ideas that are duplicated in multiple places. Where relevant, move those ideas into a single place in the docs website and introduce more hyperlinks where needed to reference that idea in multiple places.

Document ENSRainbow Decentralization

• How can I create / publish / download my own .ensrainbow file?
• How can I create / use my own ENSRainbow Labelset Server?

Originally posted by @lightwalker-eth in #612 (comment)

Document Introductory ENSRainbow Topics

There's a nice opportunity for us to document some key ideas for people who don't know what the ENSRainbow project is all about. For example:

• The problem: Unknown labels. What are they? How are they formatted? What causes them? Why are they forever a consideration in the ENS protocol? How do they influence indexing ENS data? How do they influence apps (and user interfaces) building on ENS?
  • Note: I believe we already have many of these ideas at least partially documented somewhere in our code. Suggest to make maximum use language to describe these ideas that we've already developed.
• Related background information: Ex: labels, labelhashes, keccak256, rainbow tables
• The solution: How ENSRainbow works to mitigate the problem.

[djstrong]

We want to create a conversion tool from CSV to .ensrainbow format (maybe with optional labelhash). Needs to check if CSV can support all characters.