Revert "remove draft/resume-0.5"

This reverts commit ba21987d03.

irc/help.go

@@ -129,6 +129,14 @@ longer away.`,
 
 BATCH initiates an IRCv3 client-to-server batch. You should never need to
 issue this command manually.`,
+	},
+	"brb": {
+		text: `BRB [message]
+
+Disconnects you from the server, while instructing the server to keep you
+present for a short time window. During this window, you can either resume
+or reattach to your nickname. If [message] is sent, it is used as your away
+message (and as your quit message if you don't return in time).`,
 	},
 	"cap": {
 		text: `CAP <subcommand> [:<capabilities>]
@@ -487,6 +495,12 @@ Registers an account in accordance with the draft/register capability.`,
 		text: `REHASH
 
 Reloads the config file and updates TLS certificates on listeners`,
+	},
+	"resume": {
+		text: `RESUME <oldnick> [timestamp]
+
+Sent before registration has completed, this indicates that the client wants to
+resume their old connection <oldnick>.`,
 	},
 	"time": {
 		text: `TIME [server]