Add duplicate detection tip to 'Creating an issue' docs

When creating an issue, GitHub now surfaces potential duplicate issues
inline once the title is filled out and the body reaches 100 characters.
This update adds a tip callout to the 'Creating an issue from a repository'
section explaining the behavior.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: sunnyi101

content/issues/tracking-your-work-with-issues/using-issues/creating-an-issue.md

@@ -45,6 +45,14 @@ Issues can be used to keep track of bugs, enhancements, or other requests. For m
    ![Screenshot of the template chooser for an issue. Below the template choices, a link, labeled "Open a blank issue," is outlined in dark orange.](/assets/images/help/issues/blank-issue-link.png)
 {% data reusables.repositories.type-issue-title-and-description %}
    To cross-reference a related discussion, paste the discussion's URL into the issue description.
+
+   {% ifversion fpt or ghec %}
+
+   > [!TIP]
+   > As you type, {% data variables.product.github %} may suggest potential duplicate issues that already exist in the repository. If a suggestion looks relevant, you can click through to the existing issue instead of creating a new one. These suggestions appear once the title is filled out and the body reaches 100 characters, and up to three existing issues may be shown. The suggestions are non-blocking and do not prevent you from creating your issue.
+
+   {% endif %}
+
 {% data reusables.repositories.assign-an-issue-as-project-maintainer %}
 {% data reusables.repositories.submit-new-issue %}