doc/lightning-decode.7: Update the doc

doc/lightning-decode.7.md

@@ -15,6 +15,7 @@ The **decode** RPC command checks and parses:
   or `LIGHTNING:`) as specified by the BOLT 11 and BOLT 12
   specifications.
 - a *rune* as created by lightning-commando-rune(7).
+- a *encrypted_blob* which contains the content of emergency.recover file.
 
 It may decode other formats in future.
 
@@ -24,7 +25,7 @@ RETURN VALUE
 [comment]: # (GENERATE-FROM-SCHEMA-START)
 On success, an object is returned, containing:
 
-- **type** (string): what kind of object it decoded to (one of "bolt12 offer", "bolt12 invoice", "bolt12 invoice\_request", "bolt11 invoice", "rune")
+- **type** (string): what kind of object it decoded to (one of "bolt12 offer", "bolt12 invoice", "bolt12 invoice\_request", "bolt11 invoice", "rune", "encrypted_blob")
 - **valid** (boolean): if this is false, you *MUST* not use the result except for diagnostics!
 
 If **type** is "bolt12 offer", and **valid** is *true*:
@@ -281,6 +282,9 @@ If **type** is "rune", and **valid** is *false*:
   - the following warnings are possible:
     - **warning\_rune\_invalid\_utf8**: the rune contains invalid UTF-8 strings
 
+If **type** is "encrypted_blob":
+  - **decrypted_blob** (hex): The decrypted blob
+
 [comment]: # (GENERATE-FROM-SCHEMA-END)
 
 AUTHOR