[Buildbot] #3097: document waited_for arg to addBuildset methods

[Buildbot trac]

#3097: document waited_for arg to addBuildset methods
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Reporter:  dustin       |       Owner:  dustin
    Type:  enhancement  |      Status:  new
Priority:  major        |   Milestone:  0.9.0
 Version:               |  Resolution:
Keywords:  docs         |
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Changes (by sa2ajj):

 * keywords:   => docs


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Ticket URL: <http://trac.buildbot.net/ticket/3097#comment:1>
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