lean into examples

examples/sorting-by-functions/sorting-by-functions.sh

@@ -0,0 +1,10 @@
+# Running our program shows a list sorted by string
+# length, as desired.
+$ go run sorting-by-functions.go 
+[kiwi peach banana]
+
+# By following this same pattern of creating a custom
+# type, implementing the three `Interface` methods on that
+# type, and then calling sort.Sort on a collection of that
+# custom type, we can sort Go slices by arbitrary
+# functions.