docs: add usage output to the readme to give an idea.

README.md

@@ -1,6 +1,20 @@
 # mknative
 
-Some wrappers around nativefier.
+Some bash wrappers around nativefier to generate standalone electron apps.
+
+## Usage
+
+```
+mknative
+========
+Basic Usage: $ mknative [-u] -n NativeExample -s https://example.com       
+---------------------------------------------------------------------------
+  -n NativeExample             installed application name (basically an id)
+  -s https://example.com       website address                             
+  -u                [optional] uninstall                                   
+  -i example.com    [optional] domain name to fetch favicon from.          
+  -e '--extra-args' [optional] pass some extra args to nativefier build.   
+```
 
 ## Installation