Merge branch...

Merge branch '25144-gitlab-ce-mattermost-slash-command-for-issue-create-needs-better-documentation' into 'master'

Resolve "gitlab-ce mattermost slash command for issue create needs better documentation"

## What does this MR do?

Updates the documentation and the <kbd>help</kbd> command to be clearer, having the keys used to add a newline in chat clients (both Mattermost and Slack). 

## Are there points in the code the reviewer needs to double check?

* Are the available commands (via <kbd>help</kbd>) being formatted as `<code>` ?

## Why was this MR needed?

`\n` represents a new line character and doesn't communicate how the user should input the command. Also, to be correct, the documentation should use `<kbd>` instead of `<code>` for user input ([see HTML5 specification](https://www.w3.org/TR/html5/text-level-semantics.html#the-kbd-element))

## Screenshots (if relevant)

| Mattermost | Docs |
| --- | --- |
| ![image](/uploads/539526a14bfd551b7e732dd96c5b7581/image.png) | ![image](/uploads/e3eb099f86c5a32ce3b8954e72c29848/image.png) |

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [ ] All builds are passing

## What are the relevant issue numbers?

Closes #25144

See merge request !7850

changelogs/unreleased/25144-gitlab-ce-mattermost-slash-command-for-issue-create-needs-better-documentation.yml

+---
+title: Improve help message for issue create slash command
+merge_request: 7850
+author: 

doc/project_services/mattermost_slash_commands.md

@@ -65,7 +65,7 @@ the administrator console.
 
 ### Step 3. Create a new custom slash command in Mattermost
 
-Now that you have enabled the custom slash commands in Mattermost and opened
+Now that you have enabled custom slash commands in Mattermost and opened
 the Mattermost slash commands service in GitLab, it's time to copy these values
 in a new slash command.
 
@@ -128,20 +128,16 @@ GitLab using the Mattermost commands.
 
 ## Available slash commands
 
-The available slash commands so far are:
+The available slash commands are:
 
 | Command | Description | Example |
 | ------- | ----------- | ------- |
-| `/<trigger> issue create <title>\n<description>` | Create a new issue in the project that `<trigger>` is tied to. `<description>` is optional. | `/trigger issue create We need to change the homepage` |
-| `/<trigger> issue show <issue-number>` | Show the issue with ID `<issue-number>` from the project that `<trigger>` is tied to. | `/trigger issue show 42` |
-| `/<trigger> deploy <environment> to <environment>` | Start the CI job that deploys from one environment to another, for example `staging` to `production`. CI/CD must be [properly configured][ciyaml]. | `/trigger deploy staging to production` |
+| <kbd>/&lt;trigger&gt; issue new &lt;title&gt; <kbd>⇧ Shift</kbd>+<kbd>↵ Enter</kbd> &lt;description&gt;</kbd> | Create a new issue in the project that `<trigger>` is tied to. `<description>` is optional. | <samp>/gitlab issue new We need to change the homepage</samp> |
+| <kbd>/&lt;trigger&gt; issue show &lt;issue-number&gt;</kbd> | Show the issue with ID `<issue-number>` from the project that `<trigger>` is tied to. | <samp>/gitlab issue show 42</samp> |
+| <kbd>/&lt;trigger&gt; deploy &lt;environment&gt; to &lt;environment&gt;</kbd> | Start the CI job that deploys from one environment to another, for example `staging` to `production`. CI/CD must be [properly configured][ciyaml]. | <samp>/gitlab deploy staging to production</samp> |
 
-To see a list of available commands that can interact with GitLab, type the
-trigger word followed by `help`:
-
-```
-/my-project help
-```
+To see a list of available commands to interact with GitLab, type the
+trigger word followed by <kbd>help</kbd>. Example: <samp>/gitlab help</samp>
 
 ![Mattermost bot available commands](img/mattermost_bot_available_commands.png)
 

lib/gitlab/chat_commands/issue_create.rb

@@ -8,7 +8,7 @@ module Gitlab
       end
 
       def self.help_message
-        'issue new <title>\n<description>'
+        'issue new <title> *`⇧ Shift`*+*`↵ Enter`* <description>'
       end
 
       def self.allowed?(project, user)