Add Makefile module for building documentation.

make-linux.mk

@@ -17,6 +17,8 @@
 #   clean: removes all built files, objects, other trash
 #
 
+GENERATED_FILES :=
+
 # Automagically pick clang or gcc, with preference for clang
 # This is only done if we have not overridden these with an environment or CLI variable
 ifeq ($(origin CC),default)
@@ -115,6 +117,7 @@ installer: one FORCE
 	./ext/installfiles/linux/buildinstaller.sh
 
 clean: FORCE
+	$(RM) -r ${GENERATED_FILES}
 	rm -rf *.so *.o netcon/*.a node/*.o controller/*.o osdep/*.o service/*.o ext/http-parser/*.o ext/lz4/*.o ext/json-parser/*.o $(OBJS) zerotier-one zerotier-idtool zerotier-cli zerotier-selftest zerotier-netcon-service build-* ZeroTierOneInstaller-* *.deb *.rpm .depend netcon/.depend
 	# Remove files from all the funny places we put them for tests
 	find netcon -type f \( -name '*.o' -o -name '*.so' -o -name '*.1.0' -o -name 'zerotier-one' -o -name 'zerotier-cli' -o -name 'zerotier-netcon-service' \) -delete
@@ -129,3 +132,7 @@ official: FORCE
 	make ZT_OFFICIAL_RELEASE=1 installer
 
 FORCE:
+
+DOC_DIR = doc
+
+include ${DOC_DIR}/module.mk