Encouraging for user installation

Based on interactions with customers and internal conversations, we think this is better because:
* The user doesn't need the super user access, for example when a CI user run against a prebaked Docker image
* We know exactly where the binary gets installed as per PEP-370, which make trouble-shooting easier for those who are less familiar with Python.

README.md

@@ -1,9 +1,11 @@
 # Installation
 
 ```shell
-pip3 install launchable
+pip3 install --user launchable
 ```
 
+This creates executable `~/.local/bin/launchable` that should be on your `PATH`. See [PEP-370](https://www.python.org/dev/peps/pep-0370/) for further details.
+
 ## Set your API token
 
 ```shell