Retire Amended RECs

[frivoal]

This is a possible solution to #137

[dwsinger]

do we need a Note instead pointing out our inability to revise in teh absence of an owning WG?

[frivoal]

@dwsinger,

do we need a Note

Seems reasonable to me. I've updated the pull request with such a note, and a bit of editorial massaging of surrounding text to make the Team's ability to do class 1 & 2 changes more readable.

[frivoal]

In response to @plehegar 's concern that using candidate corrections instead of amended RECs might lower expectations in terms of the rigor with which the team does maintenance-without-a-WG, I've added some extra requirements.

Re-review welcome.

[tantek]

This looks like a good simplification.