Update one-line description in README (#743)

Author: mtlynch

README.md

@@ -10,7 +10,7 @@
 
 ## Overview
 
-PicoShare is a minimalist service that allows you to share files easily.
+PicoShare is a minimalist, self-hosted web app that makes it easy to share files on the web without restrictions on size, file type, or media format.
 
 - [Live demo](https://demo.pico.rocks)