Update MANUAL.md to reflect removal of ACC command

Commit f920d3b "fix #530, #721" removed the ACC command, update
the manual to reflect this.

docs/MANUAL.md

@@ -161,15 +161,14 @@ In this section, we'll explain and go through using various features of the Orag
 In most IRC servers you can use `NickServ` to register an account. You can do the same thing with Oragono, by default, with no other software needed!
 
 These are the two ways you can register an account, either one will work:
+To register an account, use:
 
-    /QUOTE ACC REGISTER <username> * passphrase <password>
     /NS REGISTER <password>
 
-This is the way to go if you want to use a regular password. `<username>` and `<password>` are your username and password, respectively; if you go the `/NS REGISTER` route, then your current nickname will become your username. Your password cannot contain spaces, but make sure to use a strong one anyway.
+This is the way to go if you want to use a regular password. `<password>` is your password, your current nickname will become your username. Your password cannot contain spaces, but make sure to use a strong one anyway.
 
-If you want to use a TLS client certificate instead of a password to authenticate (`SASL EXTERNAL`), then you can use the commands below to do so. (If you're not sure what this is, don't worry – just use the above password method to register an account.)
+If you want to use a TLS client certificate instead of a password to authenticate (`SASL EXTERNAL`), then you can use the command below to do so. (If you're not sure what this is, don't worry – just use the above password method to register an account.)
 
-    /QUOTE ACC REGISTER <username> * certfp *
     /NS REGISTER *
 
 Once you've registered, you'll need to setup SASL to login (or use NickServ IDENTIFY). One of the more complete SASL instruction pages is Freenode's page [here](https://freenode.net/kb/answer/sasl). Open up that page, find your IRC client and then setup SASL with your chosen username and password!