Added documentation for time.Duration

README.md

@@ -28,6 +28,7 @@ It's just simple, pure stdlib.
 
 * A field's type determines what [strconv](https://golang.org/pkg/strconv/) function is called.
 * All string conversion rules are as defined in the [strconv](https://golang.org/pkg/strconv/) package
+* time.Duration follows the same parsing rules as [time.ParseDuration](https://golang.org/pkg/time#ParseDuration)
 * If chaining multiple data sources, data sets are merged. 
   Later values override previous values.
   ```go

config.go

@@ -8,6 +8,8 @@
 //
 // All string conversion rules are as defined in the https://golang.org/pkg/strconv/ package.
 //
+// time.Duration follows the same parsing rules as time.ParseDuration
+//
 // If chaining multiple data sources, data sets are merged.
 //
 // Later values override previous values.
@@ -59,6 +61,7 @@ func newBuilder() *Builder {
 // Supported fields:
 //     * all int, uint, float variants
 //     * bool, struct, string
+//     * time.Duration
 //     * slice of any of the above, except for []struct{}
 // It returns an error if:
 //     * struct contains unsupported fields (pointers, maps, slice of structs, channels, arrays, funcs, interfaces, complex)