Use place holder for the destination host in the push mirror URL

Signed-off-by: Juergen Kosel <juergen.kosel@gmx.de>

doc/workflow/repository_mirroring.md

@@ -92,7 +92,7 @@ The repository will push soon. To force a push, click the appropriate button.
 
 1. On the destination GitLab instance, create a [personal access token](../user/profile/personal_access_tokens.md) with `API` scope.
 1. On the source GitLab instance:
-  1. Fill in the **Git repository URL** field using this format: `https://oauth2@gitlab.com/<your_gitlab_group_or_name>/<your_gitlab_project>.git`.
+  1. Fill in the **Git repository URL** field using this format: `https://oauth2@<destination host>/<your_gitlab_group_or_name>/<your_gitlab_project>.git`.
   1. Fill in **Password** field with the GitLab personal access token created on the destination GitLab instance.
   1. Click the **Mirror repository** button.