Editorial: add enumerated attribute table for formmethod

[keithamus]

Per #9832 (comment) I've edited the method/formmethod enumerated attribute table.

I've changed the state names to be capitalized to match the comment @domenic made about inconsistent casing. This is probably one of the more compelling examples in that two of these states are HTTP verbs where the case is implicitly dictated. Thoughts?

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/form-control-infrastructure.html ( diff )

[domenic]

This is probably one of the more compelling examples in that two of these states are HTTP verbs where the case is implicitly dictated. Thoughts?

To me, GET and POST feels slightly better. (Although I'm happy with changing dialog -> Dialog.) The rule is, I guess, "use title case"; if you were going to write about those HTTP verbs in a title, we would keep them all-capitalized.

[annevk]

I think one I reviewed yesterday was all lowercase. I'm fine either way though.

[domenic]

Thank you!