Recipient types are case dependent in REST API calls

Looking at the documentation I kept trying "to" but it failed with
"invalid JSON".

Then I stumbled on the thread in http://g/gerritcodereview-team/c/PMf4XK_DL0Y/m/n2XSKHeCCAAJ
which said that the value should be "TO".

Change-Id: I35aa061439b499e0c80cdc9858ed2f79f1a87b4d
diff --git a/Documentation/user-notify.txt b/Documentation/user-notify.txt
index 128bae6..20ad07c 100644
--- a/Documentation/user-notify.txt
+++ b/Documentation/user-notify.txt
@@ -11,9 +11,9 @@
 
 Those are the available recipient types:
 
-* `to`: The standard To field is used; addresses are visible to all.
-* `cc`: The standard CC field is used; addresses are visible to all.
-* `bcc`: SMTP RCPT TO is used to hide the address.
+* `TO`: The standard To field is used; addresses are visible to all.
+* `CC`: The standard CC field is used; addresses are visible to all.
+* `BCC`: SMTP RCPT TO is used to hide the address.
 
 [[user]]
 == User Level Settings