Build: Fix documentation generation issues

This patch fixes some issues related to the documents
generation, in particular:

-- Fix an issue with pdflatex generation for case
   sensitive shells such as bash
-- Introduce support for png and jpg images in
   rst documents

Change-Id: I379ac3bedae386c1ad7de96380d7d0fc64fb40fd
Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
diff --git a/cmake/SphinxCopyDoc.cmake b/cmake/SphinxCopyDoc.cmake
index ff21c8d..0dc1b71 100644
--- a/cmake/SphinxCopyDoc.cmake
+++ b/cmake/SphinxCopyDoc.cmake
@@ -43,6 +43,8 @@
 		RELATIVE "${TFM_ROOT_DIR}"
 		"${TFM_ROOT_DIR}/*.md"
 		"${TFM_ROOT_DIR}/*.rst"
+		"${TFM_ROOT_DIR}/*.png"
+		"${TFM_ROOT_DIR}/*.jpg"
 		"${TFM_ROOT_DIR}/dco.txt")
 
 #Subtract exluded files from copy files