Install documentation files on make install.

Let the Makefile install these files on all systems, instead
of having explicit handling of them in the redhat spec and
debian configurations.

Makefile.am

@@ -7,6 +7,8 @@ DISTCHECK_CONFIGURE_FLAGS = \
 
 EXTRA_DIST = README.rst LICENSE vmod-example.spec debian
 
+doc_DATA = README.rst LICENSE
+
 dist_man_MANS = vmod_example.3
 MAINTAINERCLEANFILES = $(dist_man_MANS)