Added "Code Reviews" section. Fixes sendgrid#76

Author: Pawka

CONTRIBUTING.md

@@ -9,6 +9,7 @@ Hello! Thank you for choosing to help contribute to one of the SendGrid open sou
 - [Testing](#testing)
 - [Style Guidelines & Naming Conventions](#style-guidelines-and-naming-conventions)
 - [Creating a Pull Request](#creating-a-pull-request)
+- [Code Reviews](#code-reviews)
 
 <a name="roadmap"></a>
 We use [Milestones](https://github.com./sendgrid/php-http-client/milestones) to help define current roadmaps, please feel free to grab an issue from the current milestone. Please indicate that you have begun work on it to avoid collisions. Once a PR is made, community review, comments, suggestions and additional PRs are welcomed and encouraged.
@@ -191,4 +192,8 @@ Please run your code through:
 7. [Open a Pull Request](https://help.github.com./articles/using-pull-requests/)
     with a clear title and description against the `master` branch. All tests must be passing before we will review the PR.
 
+<a name="code-reviews"></a>
+## Code Reviews
+If you can, please look at open PRs and review them. Give feedback and help us merge these PRs much faster! If you don't know how, Github has some great [information on how to review a Pull Request](https://help.github.com./articles/about-pull-request-reviews/).
+
 If you have any additional questions, please feel free to [email](mailto:[email protected]) us or create an issue in this repo.