Add not maintained notice

Author: ferndot

README.md

@@ -1,6 +1,8 @@
-# Firetext
+# Firetext (Not Maintained)
 ## About
 
+>**Notice: Firetext is not currently being maintained. Use at your own risk.**
+
 Firetext is an open-source word processor for Firefox OS, and is [available on the Firefox Marketplace](https://marketplace.firefox.com/app/firetext).
 
 You can run Firetext on a Firefox OS device, on a [Firefox OS simulator](https://ftp.mozilla.org/pub/mozilla.org/labs/fxos-simulator/),