Admin docs contains deprecated info

Hi,

We're getting ready to deploy GRR on a larger scale, but repacking clients as described in the docs is not working because the docs are deprecated:
https://github.com/google/grr-doc/blob/master/admin.adoc#repacking-clients-with-custom-labels-multi-organization-deployments
(many of the CLI options are either renamed or doesn't exists anymore)

I also found this thread that describes the a newer way of doing it which actually is sane to the latest stable GRR release (3.1.0.2)
https://groups.google.com/forum/#!searchin/grr-users/repacking|sort:relevance/grr-users/PUpiGT9zPuw/7G5OM-yLQwAJ

For example:
root@grr:~# grr_client_build buildandrepack --template /usr/share/grr-server/grr-response-templates/templates/
Building installers for: ['AllPlatforms Context']
Repacking AllPlatforms Context as grr with labels: []
Repacking template: /usr/share/grr-server/grr-response-templates/templates/grr_3.1.0.2_amd64.deb.zip
Loading configuration from /tmp/tmp5If28L/grrd.yaml
Configuration writeback is set to /tmp/tmp5If28L/grrd.yaml
Writing back configuration to file /tmp/tmp5If28L/grrd.yaml
Build Config Error: Empty Client.server_urls
Build Config Error: Missing Client.executable_signing_public_key.
Build Config Error: CA certificate missing from config.
Repacking template /usr/share/grr-server/grr-response-templates/templates/grr_3.1.0.2_amd64.deb.zip failed: Bad configuration generated. Terminating.
Failed to repack /usr/share/grr-server/grr-response-templates/templates/grr_3.1.0.2_amd64.deb.zip.
Complete, installers for ['AllPlatforms_Context'] are in /usr/share/grr-server/executables/2017-04-24T20:55:15Z/linux_amd64_deb

I can't find grrd.yaml in the docs nor in the grr installations (done with the provided script)