Update database driver instrumentor docs for instrument_connection

[tammy-baylis-swi]

What problem do you want to solve?

I would be helpful if existing database driver instrumentors got doc and docstring updates to better describe instrument_connection and how it should be used. Currently their Usage examples show how to use instrument, but not instrument_connection. Some of the docs do not have docstring at all for instrument_connection.

Describe the solution you'd like

Update the docs and docstrings of these instrumentors that have instrument_connection methods defined:

• aiopg
• mysql-connector
• mysqlclient
• psycopg
• psycopg2
• pymysql
• sqlite3

I am excluding dbapi because it is more like a shared integration between instrumentors for concrete db drivers.

Describe alternatives you've considered

No response

Additional Context

No response

Would you like to implement a fix?

None

[beijiez]

Hey! Great issue. I'd like to take this on

[tammy-baylis-swi]

Thanks @beijiez for volunteering! Assigned to you.