Update AI Gateway Blueprint

As per https://gitlab.slack.com/archives/C051K31F30R/p1710972249450739?thread_ts=1710431031.385889&cid=C051K31F30R, we want to outline our work/goals for the AI Gateway as part of the current blueprint, this will help consolidate understanding and drive our work in AI Framework HQ (&11403) • Unassigned

doc/architecture/blueprints/ai_gateway/index.md

@@ -558,7 +558,7 @@ For more details, refer to the [Initial Set of Unit Primitives](https://gitlab.c
 
 ### Self Managed AI Gateway
 
-Self-managed instances should have their own AI Gateway, with Runway likely being the deployment method. This means part of our work will be to ensure that the AI Gateway can be deployed in a self-managed environment. This work will go hand-in-hand with the work to support locally hosted models (local inference) in support of GitLab AI features.
+Self-managed instances can either use centralized AI Gateway or have their own AI Gateway if they want to use self-deployed models, with Runway likely being the deployment method. This means part of our work will be to ensure that the AI Gateway can be deployed in a self-managed environment. This work will go hand-in-hand with the work to support locally hosted models (local inference) in support of GitLab AI features.
 
 - [Self Managed AI Gateway](https://gitlab.com/groups/gitlab-org/-/epics/13162)