Add chain prior to required name

README.md

@@ -177,13 +177,13 @@ chain_network_path = {
 chain_network_icon = {
     "mychain" = "_test_network_icon.html"
 }
-heart_beat_timeout = {
+chain_heart_beat_timeout = {
     "mychain" = 30
 }
-heart_command = {
+chain_heart_command = {
     "mychain" = "systemctl restart explorer.service"
 }
-blockscout_version = {
+chain_blockscout_version = {
     "mychain" = "v1.3.0-beta"
 }
 ```