Merge branch 'cells-1.0-note' into 'main'

Adding a note about Cells 1.0 architecture in the cells document

See merge request https://gitlab.com/gitlab-org/gitlab-development-kit/-/merge_requests/3580



Merged-by: Tiger Watson <twatson@gitlab.com>
Approved-by: Aboobacker MK <akarakath@gitlab.com>
Approved-by: Tiger Watson <twatson@gitlab.com>
Co-authored-by: Omar Qunsul <oqunsul@gitlab.com>

doc/howto/cells.md

 # Cells (Experiment)
 
+**NOTE:** This document doesn't reflect the newest Cells 1.X and 2.X architecture that
+are depicted [here](https://docs.gitlab.com/ee/architecture/blueprints/cells/index.html#cells-iterations).
+
 Support for cells in the GDK is still an Experiment.
 For more information, see [epic 7582](https://gitlab.com/groups/gitlab-org/-/epics/7582).