Move database storage section to release notes

[MadelineMurray]

If this section is only relevant for existing Tessera nodes upgrading to enable storage of privacy groups in Tessera, move to release notes. That is, if this content is not needed for new users of Tessera nodes, move to release notes.

[bgravenorst]

Reply from Krish:

not everyone looks religiously at release notes always,,

we haven’t released the feature yet,, once we release Tessera supporting privacy groups and it is adopted we can deprecate this , but until such time , this issue can be parked.