docs: removing intro-to-nx.livemd references

Author: TomasPegado

nx/lib/nx.ex

@@ -29,7 +29,7 @@ defmodule Nx do
 
   Here is a general outline of the main references in this library:
 
-    * For an introduction, see our [Intro to Nx](intro-to-nx.livemd) guide
+    * For an introduction, see our [Intro to Nx](introduction.md) guide
 
     * This module provides the main API for working with tensors
 

nx/mix.exs

@@ -57,7 +57,6 @@ defmodule Nx.MixProject do
       before_closing_body_tag: &before_closing_body_tag/1,
       extras: [
         "CHANGELOG.md",
-        "guides/intro-to-nx.livemd",
         "guides/getting_started/introduction.md",
         "guides/getting_started/installation.md",
         "guides/getting_started/quickstart.livemd",