add builder_boost_factor example

book/src/builders.md

@@ -41,7 +41,7 @@ With the `--prefer-builder-proposals` flag, the validator client will always pre
 lighthouse vc --builder-boost-factor <INTEGER>
 ```
 With the `--builder-boost-factor` flag, a percentage multiplier is applied to the builder's payload value when choosing between a
-builder payload header and payload from the paired execution node.
+builder payload header and payload from the paired execution node. For example, `--builder-boost-factor 50` will only use the builder payload if it is 2x more profitable than the local payload. 
 
 In order to configure whether a validator queries for blinded blocks check out [this section.](#validator-client-configuration)
 
@@ -156,6 +156,7 @@ You can also directly configure these fields in the `validator_definitions.yml`
   voting_keystore_password_path: /home/paul/.lighthouse/secrets/0x87a580d31d7bc69069b55f5a01995a610dd391a26dc9e36e81057a17211983a79266800ab8531f21f1083d7d84085007
   suggested_fee_recipient: "0x6cc8dcbca744a6e4ffedb98e1d0df903b10abd21"
   gas_limit: 30000001
+  builder_proposals: true
   builder_boost_factor: 80
 - enabled: false
   voting_public_key: "0xa5566f9ec3c6e1fdf362634ebec9ef7aceb0e460e5079714808388e5d48f4ae1e12897fed1bea951c17fa389d511e477"