feat: statistics flag, commented some more

internal/config/config.go

@@ -1,9 +1,10 @@
 package config
 
-// Arguments given to program.
+// Configuration settings for the program.
 type Config struct {
 	Source      Source // The source code given to the program.
 	Verbose     bool   // Whether or not to print debug logs.
 	Explanation bool   // Whether or not to print an explanation of the reduction.
 	Profile     string // If not nil, print a CPU profile during execution.
+	Statistics  bool   // Whether or not to print statistics.
 }