Document organisation

[mnot]

To my eye, it takes a long time when reading to this document to actually come to the part where it tells you how rate limiting works. Often, IETF specifications give a high-level overview of concrete operation first, then define the specific protocol elements necessary, and only minimally address history, motivation, etc.

That suggests an organisation like this:

• [x] 1. Introduction (considerably reducing the amount of background info, or moving it to an appendix)
• [x] 2. Expressing RateLimit Policies
• [x] 3. Providing RateLimit Fields
• [x] 4. Receiving RateLimit Fields
  1. Intermediaries
  2. Caching
• [x] 5. Field Definitions
• [x] 6. Examples (or in an appendix)

[ioggstream]

Thanks @mnot !!! We'll refactor :)