Fixed #6183; Typo Correction and Pyglet Docs link (#6328)

Added missing 's' character in "install". Added link to pyglet documentation.

research/a3c_blogpost/README.md

@@ -2,5 +2,5 @@
 In order to run this code, you will need the following prerequisites:
 
 * [OpenAI Gym](https://github.com/openai/gym) - `pip install gym`
-* pyglet - `pip intall pyglet` 
+* [pyglet](https://bitbucket.org/pyglet/pyglet/wiki/Home) - `pip install pyglet` 
 * [TensorFlow](https://www.tensorflow.org/install/) - `pip install tensorflow`