Update git submodules

* Update tools/repohooks from branch 'master'
  to 6078fd9aa2f5dd7241b63e495bb4e3d7210be1a3
  - README: improve config file docs
    
    Bug: None
    Test: read in gitiles
    Change-Id: If931b94cfd2235f5a7b9e946c0da3e5099455149
    
1 file changed