Update README.md

Author: achirkin

README.md

@@ -1,4 +1,8 @@
-ghcjs-base
+ghcjs-base-alt
 ==========
 
-minimal low-level base library for GHCJS, used by higher level libraries like JSC
+Minimal low-level base library for GHCJS, used by higher level libraries like JSC.
+
+This is an alternative to standard `ghcjs/ghcjs-base`;
+uses different implementation of `TypedArray`.
+An idea is to make it easier to program vector math.