BOLT 1: typo fix in definition.

Extra space after : breaks extract-formats.py.  Here's the before/after:

```
 msgdata,pong,byteslen,u16,
 msgdata,pong,ignored,byte,byteslen
 msgtype,peer_storage,7
+msgdata,peer_storage,length,u16,
+msgdata,peer_storage,blob,byte,length
 msgtype,peer_storage_retrieval,9
+msgdata,peer_storage_retrieval,length,u16,
+msgdata,peer_storage_retrieval,blob,byte,length
 tlvtype,n1,tlv1,1
 tlvdata,n1,tlv1,amount_msat,tu64,
 tlvtype,n1,tlv2,2
```

Signed-off-by: Rusty Russell <[email protected]>

Author: rustyrussell

01-messaging.md

@@ -522,14 +522,14 @@ peers to return the latest data to them using the `peer_storage_retrieval` messa
 
 1. type: 7 (`peer_storage`)
 2. data:
-   * [`u16`: `length`]
-   * [`length*byte`:`blob`]
+    * [`u16`:`length`]
+    * [`length*byte`:`blob`]
 
 
 1. type: 9 (`peer_storage_retrieval`)
 2. data:
-   * [`u16`: `length`]
-   * [`length*byte`:`blob`]
+    * [`u16`:`length`]
+    * [`length*byte`:`blob`]
 
 
 Requirements: