If your web server has Apache installed and if you have access to the .htaccess file.
Open up the .htaccess file and add this:
RewriteBase /
RewriteRule ^(.*)/$ $1.html [L]
So in your example if you access: http://www.example.com/example/
(must have trailing slash)
it will really be loading:
http://www.example.com/example.html
on the server(behind the scenes).
Remember that you need to make all of your links and image calls to be absolute. Example:
or they will not load correctly.
The alternative to this, which may be easiest, is to create actual folders.