[notification] fix documentation
The doc say precommit, the code says postcommit. The code is right.
We also clarify the documentation of another related operation looking suspiciously
wrong but actually correct.
import ConfigParser
try:
undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
except ConfigParser.NoOptionError:
pass # this conf. file was probably already migrated
else:
config.global_set_option('undo-enabled', bool(undo_actions))