editIssueComment(id, comment, cb) {
      return this._request('PATCH', `/repos/${this.__repository}/issues/comments/${id}`, {body: comment}, cb);
   }
Edit a comment on an issue
@see https://developer.github.com/v3/issues/comments/#edit-a-comment
@param {number} id - the comment id to edit
@param {string} comment - the comment to edit
@param {Requestable.callback} [cb] - will receive the edited comment
@return {Promise} - the promise for the http request