Assign self-revocation tap a number: 20 (#185)

Assign the self-revocation tap a number and list it in the TAP index.

Signed-off-by: Joshua Lock <joshuagloe@gmail.com>

Author: joshuagl

README.md

@@ -21,6 +21,7 @@
 * [TAP 17: Remove Signature Wrapper from the TUF Specification](tap17.md)
 * [TAP 18: Ephemeral identity verification using sigstore's Fulcio for TUF developer key management](tap18.md)
 * [TAP 19: Content Addressable Systems and TUF](tap19.md)
+* [TAP 20: Self-revocation](tap20.md)
 
 ## Deferred
 

revocation-tap.md tap20.mdrevocation-tap.md renamed to tap20.md

@@ -1,4 +1,4 @@
-* TAP: TBD
+* TAP: 20
 * Title: Self-revocation
 * Version: 1
 * Last-Modified: 29-Jan-2024