[dox] create dox makefile target to easily create doxygen docs

Makefile

@@ -248,6 +248,15 @@ paparazzi:
 	chmod a+x $@
 
 
+#
+# doxygen html documentation
+#
+dox:
+	$(Q)PAPARAZZI_HOME=$(PAPARAZZI_HOME) sw/tools/doxygen_gen/gen_modules_doc.py -pv
+	@echo "Generationg doxygen html documentation in doc/generated/html"
+	$(Q)( cat Doxyfile ; echo "PROJECT_NUMBER=$(./paparazzi_version)"; echo "QUIET=YES") | doxygen -
+	@echo "Done. Open doc/generated/html/index.html in your browser to view it."
+
 #
 # Cleaning
 #
@@ -296,7 +305,7 @@ run_tests:
 test: all replace_current_conf_xml run_tests restore_conf_xml
 
 
-.PHONY: all print_build_version update_google_version ground_segment ground_segment.opt \
+.PHONY: all print_build_version update_google_version dox ground_segment ground_segment.opt \
 subdirs $(SUBDIRS) conf ext libpprz multimon cockpit cockpit.opt tmtc tmtc.opt tools\
 static sim_static lpctools commands \
 clean cleanspaces ab_clean dist_clean distclean dist_clean_irreversible \