Add lean repo

Author: nguyenvukhang

generate.py

@@ -5,6 +5,7 @@
 
 z["index"] = "https://github.com/libmath/math/issues"
 z["wiki"] = "https://github.com/libmath/z/wiki"
+z["lean"] = "https://github.com/libmath/lean"
 z["stack"] = "https://github.com/libmath/math/issues/1"
 z["mods"] = (
     "https://docs.google.com/spreadsheets/d/1_6HvZEyN8qOcKPjzuB2e7hyQtPOQKUUcr2r0WQdD99k/edit?gid=1740291173"