docs(tutorial/step-7):Update tutorial/step-7 to fix grammar

Request Type: docs

How to reproduce: 

Component(s): 

Impact: medium

Complexity: small

This issue is related to: 

**Detailed Description:**

docs(tutorial/step-7):

Fixes a missing 'as'.
*Previous:*
We also have to add the modules dependencies of our app. By listing these two modules as dependencies of `phonecatApp`, ...
*New:*
We also have to add the modules *as* dependencies of our app. By listing ...

**Other Comments:**