Add Post Processing to process_record (#4892)

* Improve process_record system

Code based on @colinta's

* Rename and better handle functions

* Fix incorrect function call to process_record_user

* Add documentation for post_process_record

* Add both get_event_keycode and get_record_keycode functions

And add some comments about these functions

* Update code format

* Cleanup merge artifacts

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/understanding_qmk.md b/docs/understanding_qmk.md
index 81cedfcf5..939642425 100644
--- a/docs/understanding_qmk.md
+++ b/docs/understanding_qmk.md
@@ -162,6 +162,15 @@ The `process_record()` function itself is deceptively simple, but hidden within
 
 At any step during this chain of events a function (such as `process_record_kb()`) can `return false` to halt all further processing.
 
+After this is called, `post_process_record()` is called, which can be used to handle additional cleanup that needs to be run after the keycode is normally handled. 
+
+* [`void post_process_record(keyrecord_t *record)`]()
+  * [`void post_process_record_quantum(keyrecord_t *record)`]()
+    * [Map this record to a keycode]()
+    * [`void post_process_clicky(uint16_t keycode, keyrecord_t *record)`]()
+    * [`void post_process_record_kb(uint16_t keycode, keyrecord_t *record)`]()
+      * [`void post_process_record_user(uint16_t keycode, keyrecord_t *record)`]()
+      
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