docs(readme): add installation

Author: BRonen

README.md

@@ -1,2 +1,11 @@
 # Sqlite Lean4
 
+## Installation
+
+This project depends on the sqlite3 shared library.
+
+Add this snippet to you lakefile:
+
+``` lean
+require sqlite from git "https://github.com/bronen/sqlite3-lean4" @ "master"
+```