Added "reviews" documentation (#608)

* Added "reviews" documentation

* Fixed confusing terms "reviews requests" vs "reviews"

* Updated "reviews" doc

Author: Geolim4

doc/pull_request/reviews.md

@@ -0,0 +1,46 @@
+## Pull Requests / Reviews API
+[Back to the "Pull Requests API"](../pull_requests.md) | [Back to the navigation](../README.md)
+
+### List all reviews
+
+```php
+$reviewRequests = $client->api('pull_request')->reviews()->all('twbs', 'bootstrap', 12);
+```
+
+### Create a review
+
+```php
+$client->api('pull_request')->reviews()->create('twbs', 'bootstrap', 12, array(                  
+    'event' => 'APPROVE', // Accepted values: APPROVE, REQUEST_CHANGES, COMMENT, see https://developer.github.com/v3/pulls/reviews/#input-1
+    'body' => 'OK, looks good :)',// Optional, the review body text
+    'commit_id' => $commitSha, // Optional, default value is HEAD sha
+));
+```
+
+### Get a review
+
+```php
+$client->api('pull_request')->reviews()->show('twbs', 'bootstrap', 12, $reviewId);
+```
+
+### Get comment from a review
+
+```php
+$client->api('pull_request')->reviews()->comments('twbs', 'bootstrap', 12, $reviewId);
+```
+
+### Dismiss a review
+**This does not remove the review but dismisses the (dis)approval status of this one**
+
+Note: To dismiss a pull request review on a protected branch, you must be a
+repository administrator or be included in the list of people or teams who can dismiss pull request reviews.
+
+```php
+$client->api('pull_request')->reviews()->remove('twbs', 'bootstrap', 12, $reviewId, 'Dismiss reason (mandatory)');
+```
+
+### Remove a review
+
+```php
+$client->api('pull_request')->reviews()->remove('twbs', 'bootstrap', 12, $reviewId);
+```