store a symbol directly inside DISPATCH_CACHE for extra roflscale
updated AS:Callbacks doc for terminator option in define_callbacks method
The change is commited at ba552764344bc0a3c25b8576ec11f127ceaa16da
remove evals from AM::Validations::Callbacks
follow the same refactor at a63a964a5d1ed02cf0df1b1a33a96ed2a9fa987b
Merge pull request #11196 from yangchenyun/remove_evals_in_am_callbacks

Remove evals from AM::Validations::Callbacks
fix typo in ActiveModel::Error docs [ci skip]
Merge pull request #11192 from charliesome/extra-roflscale

Store a symbol directly inside DISPATCH_CACHE for additional roflscale
Adding find_by in guide to methods that trigger after_find
unified the param names across all callbacks manipulation methods
_ Rename the define_callbacks params to `names`
  - in order to match the naming conventions for `get_callbacks` and `set_callbacks` at https://github.com/rails/rails/blob/master/activesupport/lib/active_support/callbacks.rb#L736-743
  - `define_callbacks` just register names(events), not define the real callback functions.
- Rename the `reset_callbacks` params
Using preferred find_by syntax in guides
Merge pull request #11204 from Gawyn/find_by-triggers-after_find

Adding find_by in guide to methods that trigger after_find
Merge pull request #11205 from Gawyn/using-preferred-find_by-syntax-in-guides

Using preferred find_by syntax in guides
Merge pull request #11195 from yangchenyun/update_doc_for_define_callbacks

updated AS:Callbacks docs, variable namings