Remove slash from document root path in Webroot example (#5293)
Remove slash from document root path in Webroot example (#5293)

It seems the document root path to the `--webroot-path`, `-w` option
can't have a trailing slash.  
Here is an example of a user who followed this example and had their
certificate signing request error out.  
https://superuser.com/questions/1273984/why-does-certbot-letsencrypt-recieve-a-403-forbidden
lmcro/letsencrypt,letsencrypt/letsencrypt,lmcro/letsencrypt,letsencrypt/letsencrypt,stweil/letsencrypt,stweil/letsencrypt