Docs: descriptions and comments 1m-char limit

doc/user/group/epics/index.md

@@ -350,6 +350,14 @@ You can [award an emoji](../../award_emojis.md) to that epic or its comments.
 
 You can [turn on notifications](../../profile/notifications.md) to be alerted about epic events.
 
+## Limits
+
+This section gives an overview of limits of Epics and an overview of their background.
+
+### Description and comment length
+
+See [Issues: Description and comment length](../../project/issues/index.md#description-and-comment-length)
+
 <!-- ## Troubleshooting
 
 Include any troubleshooting steps that you can foresee. If you know beforehand what issues

doc/user/project/issues/index.md

@@ -4,7 +4,8 @@ Issues are the fundamental medium for collaborating on ideas and planning work i
 
 ## Overview
 
-The GitLab issue tracker is an advanced tool for collaboratively developing ideas, solving problems, and planning work.
+The GitLab issue tracker is an advanced tool for collaboratively developing ideas, solving problems,
+and planning work.
 
 Issues can allow sharing and discussion of proposals before, and during,
 their implementation between:
@@ -116,8 +117,8 @@ You can sort a list of issues in several ways, for example by issue creation dat
 
 ![Issue board](img/issue_board.png)
 
-[Issue boards](../issue_board.md) are Kanban boards with columns that display issues based on their labels
-or their assignees**(PREMIUM)**. They offer the flexibility to manage issues using
+[Issue boards](../issue_board.md) are Kanban boards with columns that display issues based on their
+labels or their assignees**(PREMIUM)**. They offer the flexibility to manage issues using
 highly customizable workflows.
 
 You can reorder issues within a column. If you drag an issue card to another column, its
@@ -200,3 +201,18 @@ Feature.enable(:save_issuable_health_status)
 - [Issues API](../../../api/issues.md)
 - Configure an [external issue tracker](../../../integration/external-issue-tracker.md)
   such as Jira, Redmine, or Bugzilla.
+
+## Limits
+
+This section gives an overview of limits of Issues and an overview of their background.
+
+### Description and comment length
+
+> Introduced in [GitLab 12.2](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/61974).
+
+Descriptions and comments on [issuable](../../../development/issuable-like-models.md) can be no
+longer than 1 million characters.
+
+Previously, there was no limit to issuable description size, which created a
+[possibility of a DoS attack](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/61974) by allowing
+very long descriptions. It's possible that we will set this limit to a lower number in the future.

doc/user/project/merge_requests/index.md

@@ -10,12 +10,12 @@ to source code that exist as commits on a given Git branch.
 ![Merge request view](img/merge_request.png)
 
 A Merge Request (**MR**) is the basis of GitLab as a code collaboration and version
-control platform. It is as simple as the name implies: a _request_ to _merge_ one
+control platform. It's exactly as the name implies: a _request_ to _merge_ one
 branch into another.
 
 ## Use cases
 
-A. Consider you are a software developer working in a team:
+A. Consider you're a software developer working in a team:
 
 1. You checkout a new branch, and submit your changes through a merge request
 1. You gather feedback from your team
@@ -61,7 +61,7 @@ So far, the navigation tabs present in merge requests to display **Discussion**,
 widget.
 
 To facilitate this navigation without having to scroll up and down through the page
-to find these tabs, based on user feedback, we are experimenting with a new positioning
+to find these tabs, based on user feedback, we're experimenting with a new positioning
 of these tabs. They are now located at the top of the merge request, with a new
 **Overview** tab, containing the description of the merge request followed by the
 widget. Next to **Overview**, you can find **Pipelines**, **Commits**, and **Changes**.
@@ -124,3 +124,11 @@ There are two main ways to have a merge request flow with GitLab:
 1. Working with forks of an authoritative project
 
 [Learn more about the authorization for merge requests.](authorization_for_merge_requests.md)
+
+## Limits
+
+This section gives an overview of limits of Merge Requests and an overview of their background.
+
+### Description and comment length
+
+See [Issues: Description and comment length](../issues/index.md#description-and-comment-length)