✨ feat(github): add github issue sync docs (#15408)

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## DESCRIBE YOUR PR

Add docs for new issue sync integrations features. Looks similar to Jira
& Azure DevOps docs


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---------

Co-authored-by: Shannon Anahata <[email protected]>
Co-authored-by: Shannon Anahata <[email protected]>

Author: 3 people

docs/organization/integrations/source-code-mgmt/github/img/github-sync.png

@@ -284,6 +284,37 @@ Here, you'll be able to create or link GitHub issues.
 
 ![Create GitHub issue form](./img/github-create-issue.png)
 
+### Issue Sync
+
+To minimize duplication in issue tracking, you can sync comments, assignees, and status updates for Sentry issues to Github issues and vice versa. When you delegate an issue to an assignee or update a status on Github, the updates will also populate in Sentry. When you resolve an issue in Sentry, the issue status will automatically update in Github. When Github issues are marked as closed, you can configure how the corresponding issue in Sentry should be resolved.
+
+<Alert title="Note">
+  Issue sync is available for organizations on the Team, Business, and
+  Enterprise plans.
+</Alert>
+
+To configure Issue sync, navigate to **Organization Settings** > **Integrations**, and click "Configure" next to your Github instance. On the following page, you can configure how you want information to sync between Sentry and Github.
+
+![Sync GitHub statuses to Sentry](./img/github-sync.png)
+
+#### User Mappings
+
+For assignee syncing to work properly between Sentry and Github, you'll need to set up user mappings. This ensures that when an issue is assigned to someone in Github, you can correctly assign it to the corresponding user in Sentry, and vice versa. **NOTE:** Without proper user mappings, assignee information will not sync between Sentry and Github.
+
+To set up user mappings:
+
+1. Navigate to **Organization Settings** > **Integrations** > **GitHub**.
+2. Click "Configure" next to your Github instance.
+3. Select the **User Mappings** tab.
+4. For each team member, map their GitHub username to their Sentry account.
+5. Click **Save Changes** when you're done.
+
+![Configure GitHub user mappings](./img/github-user-mappings.png)
+
+<Alert title="Important">
+  Make sure there is a 1:1 mapping between a Github user and a Sentry user. If there is not, assignee syncing will not work.
+</Alert>
+
 ### Resolve via Commit or Pull Request
 
 Once you are sending commit data, you can start resolving issues by including `fixes <SENTRY-SHORT-ID>` in your commit messages. For example, a commit message might look like: