README: Added doc for intial / save state

Feature introduced by #127

README.md

@@ -128,6 +128,23 @@ See the help screen by pressing `?` for a list of possible commands.
 ncspot will respect system proxy settings defined via the `http_proxy`
 environment variable.
 
+### Initial state
+
+The initial state can be specified in the configuration.
+It allows for example enabling shuffle per default.
+Following entries can be added to the configuration file:
+
+```
+[saved_state]
+volume = 80
+repeat = "track"
+shuffle = true
+```
+
+- `volume` needs to be an integer value between 0 and 100
+- `repeat` can be `"track"`, `"playlist"` or any other value which defaults to no
+- `shuffle` must be `"true"` or `"false"`
+
 ### Theming
 
 The color palette can be modified in the configuration. For instance, to have