fix: incorrect clickhouse dns example

The current example for the Clickhouse DSN is incorrect and will result in the client trying to use the default username, database, and password regardless of what is set in the DSN. This change fixed the DNS example to be correct for the current versions of the clickhouse-go client.

Author: xkisu

database/clickhouse/README.md

@@ -1,6 +1,6 @@
 # ClickHouse
 
-`clickhouse://host:port?username=user&password=qwerty&database=clicks&x-multi-statement=true`
+`clickhouse://username:password@host:port/database=clicks?x-multi-statement=true`
 
 | URL Query  | Description |
 |------------|-------------|