Update guard.md

Update grammar

Author: arungurung

docs/concept/guard.md

@@ -21,7 +21,7 @@ Suppose you have many shared local hooks.
 Instead of duplicating an existing hook, you can define a shared hook scope using `guard`.
 
 ---
-**Guard** lets you inject multiple life-cycle events into multiple routes at once. Guard is useful when you have listen to same life-cycle events in the multiple routes, for example: logging, schema validation, or error handling.
+**Guard** lets you inject multiple life-cycle events into multiple routes at once. Guard is useful when you have to listen to the same life-cycle event in multiple routes, for example: logging, schema validation, or error handling.
 
 To encapsulate all hooks into the scope, instead of writing:
 ```typescript