Added doc entry on nested key access
diff --git a/README.md b/README.md
index 885b6d8..4e72e97 100644
--- a/README.md
+++ b/README.md
@@ -237,6 +237,71 @@
fmt.Println("verbose enabled")
}
+### Accessing nested keys
+
+The accessor methods also accept formatted paths to deeply nested keys.
+For example, if the following JSON file is loaded:
+
+```
+{
+ "host": {
+ "address": "localhost",
+ "port": 5799
+ },
+ "datastore": {
+ "metric": {
+ "host": "127.0.0.1",
+ "port": 3099
+ },
+ "warehouse": {
+ "host": "198.0.0.1",
+ "port": 2112
+ }
+ }
+}
+
+```
+
+Viper can access a nested field by passing a `.` delimited path of keys:
+```
+GetString("datastore.metric.host") // (returns "127.0.0.1")
+```
+
+This obeys the precendense rules established above; the search for the root key
+(in this examole, `datastore`) will cascade through the remaining configuration registries
+until found. The search for the subkeys (`metric` and `host`), however, will not.
+
+For example, if the `metric` key was not defined in the configuration loaded
+from file, but was defined in the defaults, Viper would return the zero value.
+
+On the other hand, if the primary key was not defined, Viper would go through the
+remaining registries looking for it.
+
+Lastly, if there exists a key that matches the delimited key path, its value will
+be returned instead. E.g.
+
+```
+{
+ "datastore.metric.host": "0.0.0.0",
+ "host": {
+ "address": "localhost",
+ "port": 5799
+ },
+ "datastore": {
+ "metric": {
+ "host": "127.0.0.1",
+ "port": 3099
+ },
+ "warehouse": {
+ "host": "198.0.0.1",
+ "port": 2112
+ }
+ }
+}
+
+GetString("datastore.metric.host") //returns "0.0.0.0"
+```
+
### Marshaling
You also have the option of Marshaling all or a specific value to a struct, map, etc.
