[gimp] gitlab: update Container Registry link.

[Jehan <jehanp src gnome org>]

commit 9f385b287f6f8b273dd8d82505ad15606a510189
Author: Jehan <jehan girinstud io>
Date:   Sun Sep 27 00:47:19 2020 +0200

    gitlab: update Container Registry link.
    
    Apparently the docs changed so the anchor is broken (and contributors
    are confused). Also the docs now says that Container Registry is enabled
    by default. I assume this must be a recent change which is not available
    yet in GNOME's Gitlab instance. So we must ask people to do the opposite
    of what the docs says.

 .gitlab/merge_request_templates/default.md | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab/merge_request_templates/default.md b/.gitlab/merge_request_templates/default.md
index aec19627ab..d5ab98c39b 100644
--- a/.gitlab/merge_request_templates/default.md
+++ b/.gitlab/merge_request_templates/default.md
@@ -8,5 +8,8 @@ Contribution guidelines:
 - Check the following option when making your request:
   "*Allow commits from members who can merge to the target branch.*"
 
-- Enable the container registry for your repository:
-  https://docs.gitlab.com/ee/user/packages/container_registry/#enable-the-container-registry-for-your-project
+- Enable the container registry for your repository by following this
+  documentation, but enabling the feature instead of disabling it
+  (unlike what the docs says, Container Registry is disabled by default
+  on our Gitlab instance):
+  https://docs.gitlab.com/ee/user/packages/container_registry/#disable-the-container-registry-for-a-project