adding small usage note for bitmasks

types/bitmasks.go

@@ -1,5 +1,36 @@
 package types
 
+/*
+	See https://yourbasic.org/golang/bitmask-flag-set-clear/ for more information.
+	To use this, set constants like thus:
+	
+	const (
+		OPT1 types.MaskBit = 1 << iota
+		OPT2
+		OPT3
+		// ...
+	)
+
+	type Object struct {
+		Opts BitMask
+	}
+
+	o := Object{
+		BitMask: uint8(0)
+	}
+
+	o.AddFlag(OPT1)
+	o.AddFlag(OPT3)
+
+
+	This would return true:
+		o.HasFlag(OPT1)
+	As would this:
+		o.HasFlag(OPT3)
+	But this would return false:
+		o.HasFlag(OPT2)
+
+*/
 type BitMask interface {
 	HasFlag(bit MaskBit) bool
 	AddFlag(bit MaskBit)