Improve consistency in countBy method description (#10313)

Author: AhmedAlaa4611

Diff for: collections.md

@@ -624,7 +624,7 @@ $counted->all();
 // [1 => 1, 2 => 3, 3 => 1]
 ```
 
-You pass a closure to the `countBy` method to count all items by a custom value:
+You may pass a closure to the `countBy` method to count all items by a custom value:
 
 ```php
 $collection = collect(['[email protected]', '[email protected]', '[email protected]']);