Implemented pull request review comments API

Octokit/Models/Request/PullRequestReviewCommentCreate.cs

@@ -0,0 +1,28 @@
+using Octokit.Internal;
+
+namespace Octokit
+{
+    public class PullRequestReviewCommentCreate : RequestParameters
+    {
+        /// <summary>
+        /// The text of the comment.
+        /// </summary>
+        public string Body { get; set; }
+
+        /// <summary>
+        /// The SHA of the commit to comment on.
+        /// </summary>
+        [Parameter(Key = "commit_id")]
+        public string CommitId { get; set; }
+
+        /// <summary>
+        /// The relative path of the file to comment on.
+        /// </summary>
+        public string Path { get; set; }
+
+        /// <summary>
+        /// The line index in the diff to comment on.
+        /// </summary>
+        public int Position { get; set; }
+    }
+}