Add section on connecting to databases/datastores

[kitsonk]

The top most searched for terms in the manual are all related to connecting to databases/datastores and we really lack this type of coverage in the manual. We should have a section dedicated this and ensure we provide details on use cases for the following:

• Indicate that localStorage exists by default in Deno
• Cover off these searched for persistence layers (in descending order of popularity over the last 30 days)
  • supabase
  • postgres
  • sqlite
  • mongo
  • mysql
  • firebase

[erfanium]

Deno team doesn't have a clear solution for drivers. we have some native drivers created by denodrivers team which are not good for now. on the other side, The Deno team wants official node drivers to be worked on Deno (ref: denoland/deno#12577).

I think first we should make a decision here. made good Deno native drivers from zero OR use node drivers via std/node?

[rahulvarshney]

A real simple "Hello World" example for Supabase would be nice, showing how to get a single value from supabase and how to print that value to index.tsx