document local multiuser mode

Author: michielbdejong

README.md

@@ -68,6 +68,13 @@ $ solid start --root path/to/folder --port 8443 --ssl-key path/to/ssl-key.pem --
 
 Solid requires SSL certificates to be valid, so you cannot use self-signed certificates. To switch off this security feature in development environments, you can use the `bin/solid-test` executable, which unsets the `NODE_TLS_REJECT_UNAUTHORIZED` flag and sets the `rejectUnauthorized` option.
 
+If you want to run in multi-user mode on localhost, do the following:
+* configure the server as such with `bin/solid-test init`
+* start the server with `bin/solid-test start`
+* visit https://localhost:8443 and register a user, for instance 'myusername'.
+* Edit your hosts file and add a line `127.0.0.1 myusername.localhost`
+* Now you can visit https://myusername.localhost:8443.
+
 ##### How do I get an SSL key and certificate?
 You need an SSL certificate from a _certificate authority_, such as your domain provider or [Let's Encrypt!](https://letsencrypt.org/getting-started/).