README: Add minimal instructions

README.md

@@ -2,3 +2,18 @@
 
 An user-facing tool for configuring local and remote machines using ansible
 collections.
+
+## Install
+
+You can install `pqrs` simply using pip:
+
+    pip install pqrs
+
+## Usage
+
+A typical workflow looks like follows:
+
+    $ pqrs init  # intializes the PQRS configuration in ~/.pqrs/
+    $ pqrs subscribe <url>  # subscribes to a given channel
+    $ pqrs configure  # select the roles from the susbcribed channels
+    $ pqrs update  # run to install roles / get updates