add requiments for development

Author: gutierri

README.md

@@ -9,6 +9,12 @@ DevDocs desktop application created with GTK3 and Python.
 To launch the application from the terminal use `devdocs-desktop [STRING]`.
 If a string is provided, the application will open the first available result page.
 
+## Requirements (for development)
+
+* python (>= 3)
+* python-gobject
+* webkitgtk (engine for GTK+ 3)
+
 ## To Do
 
 Add support for offline documentation.