Add guide for managing semantic indexing policy (#61431)

Author: demiracl

content/copilot/concepts/context/repository-indexing.md

@@ -47,6 +47,15 @@ Once an index has been created for a repository, it can be used by:
 
 > [!TIP] There is no limit to how many repositories you can index.
 
+## Semantic indexing for non-GitHub repositories
+
+{% data variables.product.prodname_copilot_short %} in {% data variables.product.prodname_vscode %} can use semantic indexing for workspace files from repositories hosted outside {% data variables.product.github %}, such as GitLab, Azure DevOps, and local repositories.
+
+This feature is controlled by policy and is disabled by default. For organizations and enterprises with {% data variables.copilot.copilot_business_short %} or {% data variables.copilot.copilot_enterprise_short %}, an enterprise owner or organization owner must explicitly set this policy to **Enabled** before members can use it. If the policy remains **Unconfigured**, the feature stays unavailable. See:
+
+* [AUTOTITLE](/copilot/how-tos/administer-copilot/manage-for-enterprise/manage-enterprise-policies)
+* [AUTOTITLE](/copilot/how-tos/administer-copilot/manage-for-organization/manage-policies)
+
 ## Excluding content from {% data variables.copilot.copilot_chat_short %} answers
 
 Enterprise or organization owners with a {% data variables.copilot.copilot_enterprise_short %} or {% data variables.copilot.copilot_business_short %} plan can define content exclusions to control the behavior of {% data variables.product.prodname_copilot %} for the {% data variables.product.prodname_copilot_short %} seats they manage. For more information, see [AUTOTITLE](/copilot/managing-copilot/managing-github-copilot-in-your-organization/setting-policies-for-copilot-in-your-organization/excluding-content-from-github-copilot).

content/copilot/reference/policy-conflicts.md

@@ -35,6 +35,7 @@ Feature, model, and privacy settings for users are set according to the **least
 | Policy | Availability matches | More information |
 | :---- | :---- | :---- |
 | {% data variables.product.prodname_copilot_short %} Metrics API | Most restrictive organization | {% ifversion ghec %}[AUTOTITLE](/rest/copilot/copilot-usage-metrics){% else %}Not applicable{% endif %} |
+| Semantic indexing for non-GitHub repositories | Most restrictive organization (only available when all organizations explicitly set **Enabled**; **Unconfigured** behaves as disabled) | [AUTOTITLE](/copilot/concepts/context/repository-indexing) |
 | Suggestions matching public code (privacy policy) | Most restrictive organization | [AUTOTITLE](/copilot/concepts/completions/code-suggestions) |
 | Allow members without a {% data variables.product.prodname_copilot_short %} license to use {% data variables.copilot.copilot_code-review_short %} in {% data variables.product.prodname_dotcom_the_website %} | Most restrictive organization | [AUTOTITLE](/copilot/responsible-use/code-review) |
 | {% data variables.product.prodname_copilot_short %} can search the web | Least restrictive organization | [AUTOTITLE](/copilot/responsible-use/chat-in-github#leveraging-a-web-search-to-answer-a-question) |