fix: mention reth in package readme (ethereum#133)

Author: h4ck3rk3y

README.md

@@ -67,7 +67,7 @@ To configure the package behaviour, you can modify your `eth2-package-params.yam
     "participants": [
         {
             //  The type of EL client that should be started
-            //  Valid values are "geth", "nethermind", "erigon" and "besu"
+            //  Valid values are "geth", "nethermind", "erigon", "besu" and "reth"
             "el_client_type": "geth",
 
             //  The Docker image that should be used for the EL client; leave blank to use the default for the client type
@@ -76,6 +76,7 @@ To configure the package behaviour, you can modify your `eth2-package-params.yam
             //  - erigon: thorax/erigon:devel
             //  - nethermind: nethermind/nethermind:latest
             //  - besu: hyperledger/besu:develop
+            //  - reth: ghcr.io/paradigmxyz/reth
             "el_client_image": "",
 
             //  The log level string that this participant's EL client should log at

src/package_io/parse_input.star

@@ -2,7 +2,8 @@ DEFAULT_EL_IMAGES = {
 	"geth":			"ethereum/client-go:latest",
 	"erigon":		"thorax/erigon:devel",
 	"nethermind":	"nethermind/nethermind:latest",
-	"besu":			"hyperledger/besu:develop"
+	"besu":			"hyperledger/besu:develop",
+	"reth": 		"ghcr.io/paradigmxyz/reth"
 }
 
 DEFAULT_CL_IMAGES = {