Update keyboard.md (#2937)

FIX minor grammatical error

docfx/articles/keyboard.md

@@ -17,7 +17,7 @@ Keyboard events are sent by the [Main Loop](mainloop.md) to the
 Application class for processing. The keyboard events are sent
 exclusively to the current `Toplevel`, this being either the default
 that is created when you call `Application.Init`, or one that you
-created an passed to `Application.Run(Toplevel)`. 
+created and passed to `Application.Run(Toplevel)`. 
 
 Flow
 ----