Add SSO login section

Manual.md

@@ -22,6 +22,14 @@ If you only have a username and password, continue clicking the button.
 From there, please fill the 2 fields and click log in. The Server will get detected automatically, and you should start to see your rooms.
 
 ### How do I log in with SSO (For example Mozilla or Element One)?
+
+SSO is the most straightforward way of logging into Fluffychat.
+
+1. You put your server's address into the field at the top (For example: `https://mozilla.org` for Mozilla)
+2. You should see the SSO login options show up. Click the one you use for login.
+3. A browser should open. Use your login details and continue until redirected to Fluffychat
+4. FluffyChat should now log in to your Matrix Account.
+
 ## In the Room list
 ### How do I start a new room?
 ### How do I start a new direct message?