improve MB_DB_CONNECTION_URI example (#14586)

The example now follows a standard jdbc uri string

docs/operations-guide/environment-variables.md

@@ -189,7 +189,7 @@ Default: `null`
 
 A JDBC-style connection URI that can be used instead of most of `MB_DB_*` like [MB_DB_HOST](#mb_db_host). Also used when certain Connection String parameters are required for the connection. The connection type requirement is the same as [MB_DB_TYPE](#mb_db_type).
 
-Example: `postgres://dbuser:dbpassword@db.example.com:port/mydb?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory`
+Example: `jdbc:postgresql://dbuser:dbpassword@db.example.com:port/mydb?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory`
 
 #### `MB_DB_DBNAME`