Updating doc comment for updated 'when' format

[braker1nine]

This is my bad. This should have been in #115

[codecov-io]

Current coverage is 78.64%

Merging #116 into master will increase coverage by +0.07% as of 9567409

@@            master    #116   diff @@
======================================
  Files           37      37       
  Stmts         2824    2824       
  Branches       678     678       
  Methods          0       0       
======================================
+ Hit           2219    2221     +2
+ Partial        189     188     -1
+ Missed         416     415     -1

Review entire Coverage Diff as of 9567409

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[braker1nine]

Hmm, this should probably be reverted since the changes in #115 were reverted. Now the docs incorrectly characterize how the when callback works. I don't want some other dev banging their head expecting it to work one way when it actually works another