sql/Makefile: Install hlr_data.sql as example together with hlr.sql

Change-Id: Id4a12252b309f03bb393fa26612c305744e14403
diff --git a/sql/Makefile.am b/sql/Makefile.am
index f71037b..1367cf2 100644
--- a/sql/Makefile.am
+++ b/sql/Makefile.am
@@ -4,4 +4,4 @@
 	$(NULL)
 
 docsdir = $(docdir)
-docs_DATA = $(srcdir)/hlr.sql
+docs_DATA = $(srcdir)/hlr.sql $(srcdir)/hlr_data.sql