Adding documentation on the sync part of the adb protocol previously missing.

In the SERVICES.TXT a missing documentation file is mentioned - SYNC.TXT. This file is supposed to contain all the godie bits of the adb protocol for pushing and pulling files. I've read the source code and documented this in the file SYNC.TXT. I've used my own documentation to create a java implementation to verify the documentation here: https://github.com/vidstige/jadb



Added line breaks at 78 characters. Added comments about remote files might be deleted.

Change-Id: I48c87c2a9fb5b59b85c72679124dfbbfa9a701bc
Signed-off-by: Samuel Carlsson <samuel.carlsson@gmail.com>