RegEx for removing .html from urls

Hi!
I want to retire a plugin on a client site that appended .html to the site urls (thus keeping original pagenames from an old site). I have almost 700 pages and all that will change is the .html should be replaced with a / (/about.html becomes /about/).

You provide the RegEx in your help:

Redirect .html pages in a directory:

Source: /blog/(.*?)\.html
Target: /$1/

Example: http://oldsite.com/blog/post-name.html => https://newsite.com/post-name/

How would I amend it to accomplish the following:

https://currentsite.com/post-name.html => https:currentsite.com/post-name/

Would it be:

Source: /(.*?)\.html
Target: /$1/

THANKS!