Add Fig as an installation method to the README

Author: ibayramli

README.md

@@ -57,6 +57,15 @@ z -b foo    # cd to the parent directory starting with foo
 
 ## Install
 
+- Fig (works with all shells)
+
+  [Fig](https://fig.io) adds apps, shortcuts, and autocomplete to your existing terminal.
+
+
+    Install `z.lua` in just one click.
+
+  <a href="https://fig.io/plugins/other/z.lua" target="_blank"><img src="https://fig.io/badges/install-with-fig.svg" /></a>
+
 - Bash:
 
   put something like this in your `.bashrc`: