update repack info

[pettai]

Update the client repack docs to reflect the latest stable release of
ggr (thx to mbushkov@)

[mbushkov]

Thanks for the PR! The problem is that the current documentation is actually correct for the GRR version in HEAD. The instructions that you suggest are correct for the current GRR release version, which is quite old.

We can still probably update the docs, but then the current instructions have to be preserved, and the ones that worked for you should be formatted into a separate block, clearly stating that these instructions apply to an older GRR version.

[pettai]

ok, is there a new GRR release planned ?

[mbushkov]

Most likely there will be a new GRR release next quarter (2017Q3).

[pettai]

Ok, we can skip my update if that's obsolete to the current code anyway. I know how to make repacked clients with labels, so I can keep those notes.
May I suggest that you make a new branch (release-3.x.y.) of the grr-doc then next GRR release occurs, so the branch stays true to the current stable release?