Explain procedural votes more fully

[GPHemsley]

Right now, votes like "On Motion to Recommit with Instructions" are only explained by saying that they are procedural votes. It would be cool if we could elaborate on what the rules of order are and exactly what each of these procedural vote types are for.

[JoshData]

We have a VoteCategory enumeration that is at least separating out some of the vote types. We may need to add some regexes for other types. Then we just need to add more explanation text in templates/vote/vote_details.html (https://github.com/govtrack/govtrack.us-web/blob/master/templates/vote/vote_details.html).