fix an error that may cause confusion

Author: Yanchao WANG

at-a-glance.rst

@@ -9,7 +9,7 @@ there is actually 2 completely different types of browser emulators out there:
 * Headless browser emulators
 * Browser controllers
 
-First type browsers are simple pure HTTP specification implementations, like
+First type browser emulators are simple pure HTTP specification implementations, like
 `Goutte`_. Those browser emulators send a real HTTP requests against an application
 and parse the response content. They are very simple to run and configure,
 because this type of emulators can be written in any available programming