Zero-conf typos and clarifications

A typo wasn't fixed before merging, and there was a confusion between
public and private channels in the rationale for `alias`.

Author: t-bast

02-peer-protocol.md

@@ -549,10 +549,10 @@ to broadcast the commitment transaction to get his funds back and open a new
 channel. To avoid this, the funder should ensure the funding transaction
 confirms in the next 2016 blocks.
 
-The `alias` here is both required for routing (since there real
-short_channel_id is unknown until confirmation), and useful to provide
-one or more aliases, even once there is a real `short_channel_id` for
-a public channel.
+The `alias` here is both required for routing (since the real
+`short_channel_id` is unknown until confirmation), and useful to provide
+one or more aliases for private channels that must be used even once a
+real `short_channel_id` is available.
 
 While a node can send multiple `alias`, it must remember all of the
 ones it has sent so it can use them should they be requested by