Update README.md

Author: rizac

README.md

@@ -34,6 +34,8 @@ metadata. The main advantages of this approach are:
 
 ## Usage
 
+For full details, please consult the [wiki page](https://github.com/rizac/stream2segment/wiki)
+
 Stream2segment is a Python library and command line application available 
 after installation via the command `s2s` on the terminal. By typing `s2s --help` you
 will see all available subcommands for downloading 
@@ -95,12 +97,12 @@ In a nutshell:
        python paramtable.py ...
        ```
          
-    2. `gui.py`: visualize downloaded data in the user browser via the plots defined in the module:
+    2. `gui.py`: visualize downloaded data in the user browser via the plots defined in the module (an example in the figure above):
        ```console
        s2s show -d download.yaml -p gui.py -c gui.yaml ...
        ```
-       (Type `s2s show --help` for details)
-
+       (Type `s2s show --help` for details).
+       
     > **Note**: the associated YAML files (`paramtable.yaml`, `gui.yaml`) are not 
       mandatory but enforce the good practice of separating configuration settings (YAML)
       and the actual Python code. This way you can experiment