Build documentation at make dist time

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@5440 d4fa192b-c00b-0410-8231-f00ffab90ce4

doc/sphinx/Makefile.am

@@ -138,3 +138,10 @@ EXTRA_DIST = \
 	tutorial/statistics.rst \
 	tutorial/troubleshooting.rst \
 	tutorial/vcl.rst
+
+dist-hook:
+	$(MAKE) html
+	cp -r $(BUILDDIR) $(distdir)
+
+distclean-local:
+	rm -r $(BUILDDIR)