fix(performance): Typo '50ms seconds' (#36861)

Update how_long_is_too_long

fix a typo

Co-authored-by: Brian Thomas Smith <brian@smith.berlin>

files/en-us/web/performance/how_long_is_too_long/index.md

@@ -28,4 +28,4 @@ For scrolling and other animations to look smooth and feel responsive, the conte
 
 ## Responsiveness goal
 
-When the user interacts with content, it is important to provide feedback and acknowledge the user's response or interaction and to do so within 100ms, preferably within 50ms. 50ms seconds feels immediate. The acknowledgment of user interaction should often feel immediate, such as a hover or button press, but that doesn't mean the completed response should be instantaneous. While a slower than 100ms reaction may create a disconnect between the user interaction and the response, a 100 to 200ms transition for a response may help the user notice the response their interaction initiated, such as a menu opening. If a response takes longer than 100ms to complete, provide some form of feedback to inform the user the interaction has occurred.
+When the user interacts with content, it is important to provide feedback and acknowledge the user's response or interaction and to do so within 100ms, preferably within 50ms. 50ms feels immediate. The acknowledgment of user interaction should often feel immediate, such as a hover or button press, but that doesn't mean the completed response should be instantaneous. While a slower than 100ms reaction may create a disconnect between the user interaction and the response, a 100 to 200ms transition for a response may help the user notice the response their interaction initiated, such as a menu opening. If a response takes longer than 100ms to complete, provide some form of feedback to inform the user the interaction has occurred.