Document how to get a specific revision when rebaselining.

Document how to get a specific revision when rebaselining.

This is helpful when using the trybots.

R=epoger@google.com

Committed: https://code.google.com/p/skia/source/detail?r=11643

[bungeman-skia, 2013-10-02 22:53:48]

I was doing something on the trybots, and another run bumped the results I was
interested in off of tip of tree, so I figured out how to do this.

[epoger, 2013-10-07 18:30:55]

LGTM

Thanks for adding this.  Good idea.

[commit-bot: I haz the power, 2013-10-07 18:31:53]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/bungeman@google.com/25653008/1

[bungeman-skia, 2013-10-07 18:41:54]

On 2013/10/07 18:31:53, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
> https://skia-tree-status.appspot.com/cq/bungeman%40google.com/25653008/1

Sigh, I was on svn at the time... and the patch on reitveld is whatever you gave
it.

[bungeman-skia, 2013-10-07 20:32:22]

Committed patchset #1 manually as r11643 (presubmit successful).