Unexplained, unlinked references in doc

[dabrahams]

http://buildbot.net/buildbot/docs/current/Scheduling-Builds.html uses a number of terms that are neither defined by that point in the document nor linked to any kind of explanation.

You could have a “quick” scheduler which used a 30 second timeout, and feeds a single “quick” Builder that uses a VC mode='update' setting.

A separate “full” scheduler would run more comprehensive tests a little while later, to catch more subtle problems. This scheduler would have a longer tree-stable-timer, maybe 30 minutes, and would feed multiple Builders (with a mode= of 'copy', 'clobber', or 'export').

The tree-stable-timer and fileIsImportant decisions are made by the Scheduler.

I think I've guessed what these things are, but it took some mental gymnastics that you could have spared me by introducing the ideas more carefully.

[dustin]

Probably the best solution is to rephrase that in general terms, since the buildbot terms are not introduced yet. Do you want to draft up some new language, and I'll commit it?

[Dustin J. Mitchell]

Better docs in concepts.texinfo

This smooths out the introduction of some concepts in the "Scheduling Builds" section. Fixes #932

Changeset: 49402abde40b4ddbe4800458c256210c159ffec2