fix: doc and tests

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

v2/string/string.go

@@ -41,6 +41,9 @@ var (
 
 	// Includes returns a predicate that tests for the existence of the search string
 	Includes = F.Curry2(F.Swap(strings.Contains))
+
+	// HasPrefix returns a predicate that checks if the prefis is included in the string
+	HasPrefix = F.Curry2(F.Swap(strings.HasPrefix))
 )
 
 func Eq(left string, right string) bool {