message: link to heat example in readme
diff: @@ -77,7 +77,9 @@ Matrix matrix multiplication, addition
  let b = &eye * &a;
  assert_eq!(a, b.to_csr());
  -For a more comple example, be sure to check out the ``examples/`` folder.
  +For a more comple example, be sure to check out the `heat diffusion`_ example.
  +
  +_`heat diffusion`: examples/heat.rs
  Documentation
  -------------
  