better readme

README.md

@@ -1,3 +1,13 @@
+Very silly terminal-based crossword solver. It can play .puz files from a variety of sources, including [Crosshare](https://crosshare.org).
+
+- Requirements: [Go](https://go.dev)
+- Build: `make`
+- Usage: `./bin/crossword <file>.puz`
+
+![demo](demo.gif)
+
+---
+
 todo
 
 - correctly calculate uiHeight with multi-line clues