Fix undesirable "No documentation available" hover hints (#279)

Returning [] as intended.

Broken since elixir-lsp/elixir_sense@efb42a7.

Author: dgutov

apps/language_server/lib/language_server/providers/hover.ex

@@ -42,7 +42,7 @@ defmodule ElixirLS.LanguageServer.Providers.Hover do
     end)
   end
 
-  defp contents(%{docs: "No documentation available"}) do
+  defp contents(%{docs: "No documentation available\n"}) do
     []
   end