Add injections for the comments extension (#66)

This adds an injection for PHP comments to allow the new "comments"
extension to work:

![Screenshot 2025-10-08 at 10 16
10 AM](https://github.com/user-attachments/assets/9e33bb82-82f3-4aec-95a3-9473a5d75544)

Ref: https://github.com/thedadams/zed-comment
Ref:
zed-industries/zed@e60a61f

Author: claytonrcarter

languages/php/injections.scm

@@ -6,6 +6,9 @@
   (#match? @injection.content "^/\\*\\*[^*]")
   (#set! injection.language "phpdoc"))
 
+((comment) @injection.content
+ (#set! injection.language "comment"))
+
 ((heredoc_body) (heredoc_end) @injection.language) @injection.content
 
 ((nowdoc_body) (heredoc_end) @injection.language) @injection.content