Fixed typo

'lines' instead of 'line' in the "multi-line input" section

Author: alaabouayed

1-js/01-getting-started/3-devtools/article.md

@@ -54,7 +54,7 @@ Now `key:Cmd+Opt+C` can toggle the console. Also, note that the new top menu ite
 
 Usually, when we put a line of code into the console, and then press `key:Enter`, it executes.
 
-To insert multiple line, press `key:Shift+Enter`.
+To insert multiple lines, press `key:Shift+Enter`.
 
 ## Summary