doc: remove broken link to permission model source code

The permission model grew enough to be splited into multiple files, the
link in the md file is broken. And as it is not part of a single file,
the best way to fix this is just remove the link, many APIs in Node.js
does not have the source code linked, this is not bad for our docs.

Signed-off-by: Juan José Arboleda <soyjuanarbol@gmail.com>
PR-URL: #58972
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: juanarbol

doc/api/permissions.md

@@ -2,8 +2,6 @@
 
 <!--introduced_in=v20.0.0-->
 
-<!-- source_link=src/permission.cc -->
-
 Permissions can be used to control what system resources the
 Node.js process has access to or what actions the process can take
 with those resources.