How to do redirect correctly?

Question

htaccess

the entire directory is dubbed, you need to redirect
from site.ru/item-20 to site.ru/item-20.html,
of course, the parameter is not 20, but can be any number.
Googled, found only from a certain get parameter to another

Answer 1

Is it this:
It is not a CNC transformation of this:
Maybe I need to dig in this direction, or I did not understand the essence of the issue?