Update stack-buttons.mdx (#7823)

fix typo

Author: thoys

website/versioned_docs/version-7.37.0/docs/stack-buttons.mdx

@@ -20,7 +20,7 @@ On Android, use the [showAsAction](#showasaction) options to control when the bu
 
 Left buttons behave like right buttons with two caveats on Android:
 
-- Only a single left button is alowed
+- Only a single left button is allowed
 - Textual left button isn't supported
 
 # Using a react component in a button