Data flow arrows

### Describe what's missing in our docs

It is not clear what these arrows in this diagram indicate. If the arrows on this graphic indicate data flow, shouldn't they point both ways? This is read as the database just pushes data to these clients and the clients never write data back to the database which I believe is not the case.

Locate the documentation page containing the attached diagram by searching for the image or surrounding diagram content. Review the diagram's arrow semantics and existing explanatory text; done means the documentation makes the direction and data-flow behavior unambiguous.

Written by the indexing model from the issue text.