multi: replace FundingLocked related docs

This commit replaces `FundingLocked` found in docs using the following
command,
```shell
find . -name "*.go" -exec sed -i '' 's/FundingLocked/ChannelReady/g' {} \;
find . -name "*.go" -exec sed -i '' 's/FundingLock/ChannelReady/g' {} \;
```

netann/chan_status_manager.go

@@ -54,7 +54,7 @@ type ChanStatusConfig struct {
 	// IsChannelActive checks whether the channel identified by the provided
 	// ChannelID is considered active. This should only return true if the
 	// channel has been sufficiently confirmed, the channel has received
-	// FundingLocked, and the remote peer is online.
+	// ChannelReady, and the remote peer is online.
 	IsChannelActive func(lnwire.ChannelID) bool
 
 	// ApplyChannelUpdate processes new ChannelUpdates signed by our node by