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 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 instances can either use GitLab-hosted 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)