COMPMID-1997: Add ACL logo to the documentation and README.md

Change-Id: Iee5be5c6725920ec174fde381ff4efc7be6c2de7
Signed-off-by: Isabella Gottardi <isabella.gottardi@arm.com>
Reviewed-on: https://review.mlplatform.org/748
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/docs/Doxyfile b/docs/Doxyfile
index 22ce889..081d497 100644
--- a/docs/Doxyfile
+++ b/docs/Doxyfile
@@ -1180,7 +1180,7 @@
 # list). For an example see the documentation.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_EXTRA_STYLESHEET  = 
+HTML_EXTRA_STYLESHEET  = ./docs/stylesheet.css
 
 # The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
 # other source files which should be copied to the HTML output directory. Note