sonic-cli-gen config update description

[dudu574]

change sonic-cli-gen config update description

Steps to reproduce the issue

1. Get sonic-yang models.
2. Generate python codes automatically and try config command.
3. Result is: Options: -?, -h, --help Show this message and exit.

Commands: add Add object in ***. delete Delete object in ***. update Add object in ***.

Describe the results you received

This is since utils' sonic-utilities-data/templates/sonic-cli-gen/config.py.j2 uses wrong description.

Describe the results you expected

Options: -?, -h, --help Show this message and exit.

Commands: add Add object in ***. delete Delete object in ***. update Update object in ***.

Additional information you deem important (e.g. issue happens only occasionally)

Output of show version

(paste your output here)