(enh) Add 3rd party Abc Notation grammar to Supported Languages (#4291)

Author: NriotHrreion

CHANGES.md

@@ -13,6 +13,7 @@ New Grammars:
 - added 3rd party Gleam grammar to SUPPORTED_LANGUAGES [Filip Hoffmann][]
 - added 3rd party L4 grammar to SUPPORTED_LANGUAGES [Thomas Gorissen][]
 - added 3rd party Bicep grammar to SUPPORTED_LANGUAGES [Anthony Martin][]
+- added 3rd party Abc Notation grammar to SUPPORTED_LANGUAGES [NriotHrreion][]
 
 Core Grammars:
 
@@ -53,6 +54,7 @@ CONTRIBUTORS
 [Thomas Gorissen]: https://github.com/serrynaimo
 [te-ing]: https://github.com/te-ing
 [Anthony Martin]: https://github.com/anthony-c-martin
+[NriotHrreion]: https://github.com/NriotHrreion
 
 
 ## Version 11.11.1

SUPPORTED_LANGUAGES.md

@@ -10,6 +10,7 @@ The table below shows the full list of languages (and corresponding classes/alia
 | 1C                      | 1c                     |         |
 | 4D                      | 4d                     |[highlightjs-4d](https://github.com/highlightjs/highlightjs-4d) |
 | ABAP                    | sap-abap, abap         |[highlight-sap-abap](https://github.com/highlightjs/highlightjs-sap-abap) |
+| Abc Notation            | abc                    |[highlightjs-abc](https://github.com/nocpiun/highlightjs-abc)|
 | ABNF                    | abnf                   |         |
 | Access logs             | accesslog              |         |
 | ActionScript            | actionscript, as       |         |