Add CLI flags

beacon_node/client/src/config.rs

@@ -75,6 +75,7 @@ pub struct Config {
     pub chain: beacon_chain::ChainConfig,
     pub eth1: eth1::Config,
     pub execution_endpoints: Option<Vec<SensitiveUrl>>,
+    pub total_terminal_difficulty_override: Option<u64>,
     pub http_api: http_api::Config,
     pub http_metrics: http_metrics::Config,
     pub monitoring_api: Option<monitoring_api::Config>,
@@ -96,6 +97,7 @@ impl Default for Config {
             sync_eth1_chain: false,
             eth1: <_>::default(),
             execution_endpoints: None,
+            total_terminal_difficulty_override: None,
             disabled_forks: Vec::new(),
             graffiti: Graffiti::default(),
             http_api: <_>::default(),