feat: meaningful comments for internal packages

internal/explanation/tracker.go

@@ -1,3 +1,5 @@
+// Package "explanation" provides a observer to gather the reasoning during the
+// reduction, and present a thorough explanation to the user for each step.
 package explanation
 
 import (
@@ -7,10 +9,12 @@ import (
 	"git.maximhutz.com/max/lambda/pkg/lambda"
 )
 
+// Track the reductions made by a reduction proess.
 type Tracker struct {
 	process *engine.Engine
 }
 
+// Attaches a new explanation tracker to a process.
 func Track(process *engine.Engine) *Tracker {
 	tracker := &Tracker{process: process}
 	process.On("start", tracker.Start)