Fix typo in BTP and better formatting in ILDCP

[MichaelKohler]

• Fixes a typo in BTP where it said one instead of two when referring to the amount of request types
• https://interledger.org/developers/rfcs/dynamic-configuration-protocol/ does not seem to correctly render the list, so I adjusted it to use sub headings rather than a 3-level-indentation list which can get hard to read.