Correct PostgreSQL DSN example on SQL_DRIVERS_INPUT.md

[Tonic8]

Relevant telegraf.conf

telegraf.conf not relevant for this Documentation issue

in the the SQL_DRIVERS_INPUT.md, the PostgreSQL DSN is not correct

`[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]`

it should be:

`postgres://[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]`

Logs from Telegraf

logs of telegraf not relevant for this Documentation issue

System info

telegraf 1.31.1

Docker

No response

Steps to reproduce

1. go on https://github.com/influxdata/telegraf/blob/master/docs/SQL_DRIVERS_INPUT.md
2. check the PostgreSQL DSN example

Expected behavior

it should be

postgres://[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]

Actual behavior

it's 👍

[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]

Additional info

No response