Provide docs for all callback entry points

[webframp]

The docs for callbacks currently say:

Callbacks are generally invoked in two places: before and after

and

There are also callbacks available prior to the execution of a command. These can also be isolated to specific commands

but it would be super helpful to know exactly what entry points are available to callback authors. So far I've seen after_config, after_create, after_config_create (also aliased to after_config_update and now template. A generate list of potential callbacks would help kill the mystery.