Fix the sentences a fresh read of README.md failed (closes #190)

A fresh read of README.md on next, sentence by sentence against
the rules on #190 and the
code, failed one sentence. The IRC listener bullet on PASS after
registration ("answers a password of the wrong length with a
NOTICE, not ERR_NEEDMOREPARAMS (461), and a stored password with a
NOTICE too") needs a second reading to see that "a stored password"
means the case where the password is accepted. It is now two short
sentences: the NOTICE on success first, then the NOTICE instead of
461 on a wrong length. Both facts match handlePassPostReg and
checkPasswordLength in internal/ircserver. Every other sentence
passed; nothing else is changed.

Model: fable-5-1

README.md

@@ -1637,9 +1637,9 @@ They behave as over the HTTP API, with the IRC syntax and these differences:
 - `KICK` without a reason uses the kicked user's nick as the reason.
 - `MOTD` sends only `375` to `376`, or `ERR_NOMOTD` (`422`) when the message of
   the day is empty, without the welcome and `LUSERS` replies.
-- `PASS` after registration answers a password of the wrong length with a
+- `PASS` after registration answers with a `NOTICE` when it stores the password.
-  `NOTICE`, not `ERR_NEEDMOREPARAMS` (`461`), and a stored password with a
+  A password of the wrong length also gets a `NOTICE`, not `ERR_NEEDMOREPARAMS`
-  `NOTICE` too.
+  (`461`).
 
 ### What IRC clients see