Add missing 'the' (#2200)

Author: jsoendermann

docs/coroutines-guide.md

@@ -10,7 +10,7 @@ coroutine-enabled primitives that this guide covers, including `launch`, `async`
 
 This is a guide on core features of `kotlinx.coroutines` with a series of examples, divided up into different topics.
 
-In order to use coroutines as well as follow the examples in this guide, you need to add a dependency on `kotlinx-coroutines-core` module as explained 
+In order to use coroutines as well as follow the examples in this guide, you need to add a dependency on the `kotlinx-coroutines-core` module as explained 
 [in the project README](../README.md#using-in-your-projects).
 
 ## Table of contents