Shelf permissions: reverted create removal

Reverted work in 847a57a49a.
Left test in but updated to new expectation.
Left migration in but removed content to prevent new pre-v23.06
upgraders loosing shelf create permission status.
Added note to permission to describe use-case.

For #4375

database/migrations/2023_06_25_181952_remove_bookshelf_create_entity_permissions.php

@@ -12,9 +12,10 @@ return new class extends Migration
      */
     public function up()
     {
-        DB::table('entity_permissions')
-            ->where('entity_type', '=', 'bookshelf')
-            ->update(['create' => 0]);
+        // Note: v23.06.2
+        // Migration removed since change to remove bookshelf create permissions was reverted.
+        // Create permissions were removed as incorrectly thought to be unused, but they did
+        // have a use via shelf permission copy-down to books.
     }
 
     /**