Improve consistency in UNICODEMAP code and docs, update docs/understanding_qmk (#4774)

* Remove unused UNICODE(n) macro, update docs

* Add note about max length of unicode_map to docs

* QK_UNICODE_MAP → QK_UNICODEMAP

* Refactor process_unicode_map

* process_unicode_map → process_unicodemap

This is done for consistency: UNICODEMAP is the method (hence UNICODEMAP_ENABLE, process_unicodemap), whereas unicode_map is the mapping table itself.

* Update references and ordering in docs/understanding_qmk

* Add additional note to docs/understanding_qmk

* &unicode_map[index] → unicode_map + index

This avoids the issue of the compiler sometimes complaining about the array index being out of range

* Update docs/getting_started_make_guide

* Update method sections in docs/feature_unicode

1 files changed, 2 insertions, 2 deletions

diff --git a/quantum/process_keycode/process_unicodemap.h b/quantum/process_keycode/process_unicodemap.h
index f6d64bb86..5764697f8 100644
--- a/quantum/process_keycode/process_unicodemap.h
+++ b/quantum/process_keycode/process_unicodemap.h
@@ -19,5 +19,5 @@
 #include "quantum.h"
 #include "process_unicode_common.h"
 
-void unicode_map_input_error(void);
-bool process_unicode_map(uint16_t keycode, keyrecord_t *record);
+void unicodemap_input_error(void);
+bool process_unicodemap(uint16_t keycode, keyrecord_t *record);