message: Updade connection prefix
  The connection prefix should be different if the DB2 dialect is different.
diff: @@ -16,3 +16,9 @@ Here's the recommended connection string:
  ```
  db2+ibm_db://{username}:{passport}@{hostname}:{port}/{database}
  ```
  +
  +There are two DB2 dialect versions implemented in SQLAlchemy. If you are connecting to a DB2 version without `LIMIT [n]` syntax, the recommended connection string to be able to use the SQL Lab is:
  +
  +```
  +ibm_db_sa://{username}:{passport}@{hostname}:{port}/{database}
  +```
  