Added info for the DiscussionsApi.

Author: gmessner

README.md

@@ -182,6 +182,7 @@ The API has been broken up into sub APIs classes to make it easier to learn and
 &nbsp;&nbsp;[AwardEmojiApi](#awardemojiapi)<br/>
 &nbsp;&nbsp;[CommitsApi](#commitsapi)<br/>
 &nbsp;&nbsp;[DeployKeysApi](#deploykeysapi)<br/>
+&nbsp;&nbsp;[DiscussionsApi](#discussionsapi)<br/>
 &nbsp;&nbsp;[EpicsApi](#epicsapi)<br/>
 &nbsp;&nbsp;[EventsApi](#eventsapi)<br/>
 &nbsp;&nbsp;[GroupApi](#groupapi)<br/>
@@ -231,6 +232,12 @@ List<Commit> commits = gitLabApi.getCommitsApi().getCommits(1234, "new-feature",
 List<DeployKey> deployKeys = gitLabApi.getDeployKeysApi().getDeployKeys();
 ```
 
+#### DiscussionsApi
+```java
+// Get a list of Discussions for the specified merge request
+List<DeployKey> deployKeys = gitLabApi.getDiscussionsApi().getMergeRequestDiscussions(projectId, mergeRequestIid);
+```
+
 #### EpicsApi
 ```java
 // Get a list epics of the requested group and its subgroups.