Convert config-split.md with Pandoc

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/docs/proposed/Makefile b/docs/proposed/Makefile
index 1c31464..7f5254f 100644
--- a/docs/proposed/Makefile
+++ b/docs/proposed/Makefile
@@ -3,6 +3,7 @@
 default: all
 
 all_markdown = \
+	       config-split.md \
 	       psa-conditional-inclusion-c.md \
 	       psa-driver-developer-guide.md \
 	       psa-driver-integration-guide.md \