Add reference to comprehensive accessible domains list for self-hosted runners (#58563)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: timrogers <116134+timrogers@users.noreply.github.com>
Co-authored-by: Tim Rogers <timrogers@github.com>
Co-authored-by: Joe Clark <31087804+jc-clark@users.noreply.github.com>

Author: 3 people

content/copilot/how-tos/use-copilot-agents/coding-agent/customize-the-agent-environment.md

@@ -186,6 +186,8 @@ When using self-hosted runners, especially with the firewall disabled, ensure yo
 * `uploads.github.com`
 * `user-images.githubusercontent.com`
 
+For a comprehensive list of other hosts that must also be allowlisted for {% data variables.product.prodname_actions %} self-hosted runners, see [AUTOTITLE](/actions/reference/runners/self-hosted-runners#accessible-domains-by-function).
+
 ## Enabling Git Large File Storage (LFS)
 
 If you use Git Large File Storage (LFS) to store large files in your repository, you will need to customize {% data variables.product.prodname_copilot_short %}'s environment to install Git LFS and fetch LFS objects.