Documentation for batch comments

Adds documentation for the new Merge Request Reviews (batch comments)
feature

doc/user/discussions/index.md

@@ -273,6 +273,67 @@ edit existing comments. Non-team members are restricted from adding or editing c
 
 Additionally locked issues can not be reopened.
 
+## Merge Request Reviews **[PREMIUM]**
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4213) in GitLab 11.4.
+
+When looking at a Merge Request diff, you are able to start a review.
+This allows you to create comments inside a Merge Request that are **only visible to you** until published,
+in order to allow you to submit them all as a single action.
+
+### Starting a review
+
+In order to start a review, simply write a comment on a diff as normal under the **Changes** tab 
+in an MR and click on the **Start a review** button.
+
+![Starting a review](img/mr_review_start.png)
+
+Once a review is started, you will see any comments that are part of this review marked `Pending`.
+All comments that are part of a review show two buttons:
+
+- **Submit review**: Submits all comments that are part of the review, making them visible to other users.
+- **Add comment now**: Submits the specific comment as a regular comment instead of as part of the review.
+
+![A comment that is part of a review](img/pending_review_comment.png)
+
+You can use [quick actions] inside review comments. The comment will show the actions that will be performed once published.
+
+![A review comment with quick actions](img/review_comment_quickactions.png)
+
+To add more comments to a review, start writing a comment as normal and click the **Add to review** button.
+
+![Adding a second comment to a review](img/mr_review_second_comment.png)
+
+This will add the comment to the review.
+
+![Second review comment](img/mr_review_second_comment_added.png)
+
+### Resolving/Unresolving discussions
+
+Review comments can also resolve/unresolve [resolvable discussions](#resolvable-discussions).
+When replying to a comment, you will see a checkbox that you can click in order to resolve or unresolve
+the discussion once published.
+
+![Resolve checkbox](img/mr_review_resolve.png) 
+![Unresolve checkbox](img/mr_review_unresolve.png)
+
+If a particular pending comment will resolve or unresolve the discussion, this will be shown on the pending
+comment itself.
+
+![Resolve status](img/mr_review_resolve2.png) 
+![Unresolve status](img/mr_review_unresolve2.png)
+
+### Submitting a review
+
+If you have any comments that have not been submitted, you will see a bar at the bottom of the screen with two buttons:
+
+- **Discard**: Discards all comments that have not been submitted.
+- **Submit review**: All comments are published. Any quick actions submitted are performed at this time.
+
+Alternatively, every pending comment has a button to submit the entire review.
+
+![MR Review bar](img/mr_review_bar.png)
+
 [ce-5022]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5022
 [ce-7125]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7125
 [ce-7527]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7527

doc/user/project/merge_requests/index.md

@@ -33,6 +33,7 @@ With GitLab merge requests, you can:
 
 With **[GitLab Enterprise Edition][ee]**, you can also:
 
+- Prepare a full review and submit it once it's ready with [Merge Request Reviews](../../discussions/index.md#merge-request-reviews) **[PREMIUM]**
 - View the deployment process across projects with [Multi-Project Pipelines](../../../ci/multi_project_pipelines.md#multi-project-pipeline-graphs) **[PREMIUM]**
 - Request [approvals](merge_request_approvals.md) from your managers **[STARTER]**
 - Analyze the impact of your changes with [Code Quality reports](code_quality.md) **[STARTER]**
@@ -149,6 +150,14 @@ you hide discussions that are no longer relevant.
 
 [Read more about resolving discussion comments in merge requests reviews.](../../discussions/index.md)
 
+## Perform a Review **[PREMIUM]**
+
+Start a review in order to create multiple comments on a diff and publish them once you're ready.
+Starting a review allows you to get all your thoughts in order and ensure you haven't missed anything
+before submitting all your comments.
+
+[Learn more about Merge Request Reviews](../../discussions/index.md#merge-request-reviews)
+
 ## Squash and merge
 
 GitLab allows you to squash all changes present in a merge request into a single