Update ADR-4 with decision

Author: Jimbo4350

docs/ADR-004-Support-only-for-mainnet-and-upcoming-eras.md

@@ -156,7 +156,7 @@ We then slowly replace the use of the existing api in cardano-api, eventually de
 
 # Decision
 
-TBD
+The ADR gets adopted in `cardano-api` and `cardano-cli`. There may be minor tweaks as it is rolled out in `cardano-cli`.
 
 # Consequences