📚 Start a proper README

Author: davep

README.md

@@ -1,11 +1,24 @@
 # textual-mandelbrot
 
+![mandelexp in action](https://raw.githubusercontent.com/davep/textual-mandelbrot/main/img/mandelexp01.png)
+![mandelexp in action](https://raw.githubusercontent.com/davep/textual-mandelbrot/main/img/mandelexp02.png)
+
 ## Introduction
 
-Barely working at the moment. Come back later.
+This packages provides a simple Mandelbrot set widget that can be used in
+[Textual](https://textual.textualize.io/) applications, and also provides an
+application that can be used to explore the classic Mandelbrot set in the
+terminal.
+
+## Installing
+
+The package can be installed using [`pipx`](https://pypa.github.io/pipx/):
 
-## TODO
+```sh
+$ pipx install textual-mandelbrot
+```
 
-Pretty much everything. Check back soon.
+Once installed you should be able to run the command `mandelexp` and the
+application will run.
 
 [//]: # (README.md ends here)