Also sync --help output with manual.

Makefile

@@ -203,8 +203,11 @@ check_docs:
 	@cat src/cmdline.cc  | grep -o -- '--[a-z][a-z]*' | sort | uniq | grep -v internaltesting > /tmp/options_in_code
 	@cat wmbusmeters.1   | grep -o -- '--[a-z][a-z]*' | sort | uniq | grep -v internaltesting > /tmp/options_in_man
 	@cat README.md | grep -o -- '--[a-z][a-z]*' | sort | uniq | grep -v internaltesting > /tmp/options_in_readme
+	@./build/wmbusmeters --help | grep -o -- '--[a-z][a-z]*' | sort | uniq | grep -v internaltesting > /tmp/options_in_binary
 	@diff /tmp/options_in_code /tmp/options_in_man
 	@diff /tmp/options_in_code /tmp/options_in_readme
+	@diff /tmp/options_in_code /tmp/options_in_binary
+	@echo "OK docs"
 
 install: $(BUILD)/wmbusmeters check_docs
 	@./install.sh $(BUILD)/wmbusmeters $(DESTDIR) $(EXTRA_INSTALL_OPTIONS)

README.md

@@ -185,6 +185,7 @@ As <options> you can use:
     --alarmshell=<cmdline> invokes cmdline when an alarm triggers
     --alarmtimeout=<time> Expect a telegram to arrive within <time> seconds, eg 60s, 60m, 24h during expected activity.
     --debug for a lot of information
+    --device=<device> override device in config files. Use only in combination with --useconfig= option
     --donotprobe=<tty> do not auto-probe this tty. Use multiple times for several ttys or specify "all" for all ttys.
     --exitafter=<time> exit program after time, eg 20h, 10m 5s
     --format=<hr/json/fields> for human readable, json or semicolon separated fields