ax(mining): replace prose comment on NewTTMiner with usage example

AX Principle 2: comments must show concrete usage, not restate the signature.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/ttminer.go

@@ -54,7 +54,8 @@ type TTMinerSummary struct {
 // MinerTypeTTMiner is the type identifier for TT-Miner miners.
 const MinerTypeTTMiner = "tt-miner"
 
-// NewTTMiner creates a new TT-Miner instance with default settings.
+// miner := mining.NewTTMiner()
+// miner.Start(ctx)
 func NewTTMiner() *TTMiner {
 	return &TTMiner{
 		BaseMiner: BaseMiner{