Add note about teleporter tubes reserved channels.

Overview.html

@@ -154,6 +154,8 @@ a {
 		<img src="img/TeleporterTubeForm.png">
 		<p>Only teleporter tubes that have the same channel will be linked together and allow items to pass through.</p>
 		<p>The button on the right toggles between "On" and "Off". When the button reads "On", the tube can receive items. Otherwise, items can only be teleported out of the tube, but not into it.</p>
+		<p>Teleporter tubes with channel names beginning with the name of a player, followed by a colon, are settable only by the specified player. This is useful for making private teleporter tube channels.</p>
+		<p>Teleporter tubes with channel names beginning with the name of a player, followed by a semicolon, are usable only by the specified player, or by other players if the tube is not "On" (unable to receive items). This allows for mail-like systems where items can be sent into private dropboxes, but can't be taken out except by the recipient.</p>
 		<p>If an item enters a teleporter tube, and there are multiple possible teleporter tubes that it can go to, a target is chosen at random from the possibilities.</p>
 		<p>Here's how you craft it:</p>
 		<img src="img/CraftTeleporterTube.png">