Insure the web RootDirectory ends in a slash.

Reported by Compctech via DOVE-Net:

"On a side note,  I had to modify the letsyncrypt.js file to get letsencrypt to
work.  I had to add a / before .well-known on lines 86 - 89 & 96."

I'm guessing this is because his sbbs.ini [Web] RootDirectory wasn't terminated with a slash.