CIP-0015: Document key revocation

CIP-0015/CIP-0015.md

@@ -89,13 +89,32 @@ Signature example:
 }
 ```
 
-#### Metadata schema
+### Revocation of a voting key
+
+A previously registered voting key can be revoked by posting another transaction
+with the two metadata fields as above, with the difference that the voting key
+and the reward address fields are absent.
+
+Revocation example:
+```
+61284: {
+ // No voting_key
+ // stake_pub - CBOR byte array
+ 2: "0xad4b948699193634a39dd56f779a2951a24779ad52aa7916f6912b8ec4702cee",
+ // slot_number
+ 4: 5479468
+}
+```
+
+The signature payload under key 61285 is formed as described above.
+
+### Metadata schema
 
 The format above can be described by the following CDDL definition:
 
 ```
 registration_cbor = {
- 61284: key_registration,
+ 61284: key_registration / key_revocation,
  61285: registration_signature
 }
 
@@ -112,6 +131,11 @@ key_registration = {
  4 : $slot_number,
 }
 
+key_revocation = {
+ 2 : $staking_pub_key,
+ 4 : $slot_number,
+}
+
 registration_signature = {
  1 : $ed25519_signature //
  2 : $ed25519_signature