[%# This Source Code Form is subject to the terms of the Mozilla Public
  # License, v. 2.0. If a copy of the MPL was not distributed with this
  # file, You can obtain one at http://mozilla.org/MPL/2.0/.
  #
  # This Source Code Form is "Incompatible With Secondary Licenses", as
  # defined by the Mozilla Public License, v. 2.0.
  #%]

Template hooks go in this directory. Template hooks are called in normal
Bugzilla templates like [[% '%' %] Hook.process('some-hook') %].
More information about them can be found in the documentation of 
Bugzilla::Extension. (Do "perldoc Bugzilla::Extension" from the main
Bugzilla directory to see that documentation.)
