Doc: Remove external libraries from documentation

This patch removes all documentes listed under the
path '/lib/ext' from the Sphynx build TOC and adds
the patch to exclusion list.

Change-Id: I7852b030b946d68b359c31ce4a785920a07f4ff5
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/docs/index.rst b/docs/index.rst
index 5ada824..6ca8c95 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -25,14 +25,6 @@
     docs/lic
 
 .. toctree::
-    :caption: Components
-    :maxdepth: 2
-    :glob:
-    :hidden:
-
-    lib/**
-
-.. toctree::
     :caption: Target platforms
     :maxdepth: 2
     :glob:
@@ -52,4 +44,4 @@
 
 --------------
 
-*Copyright (c) 2017-2019, Arm Limited. All rights reserved.*
+*Copyright (c) 2017-2020, Arm Limited. All rights reserved.*