generate a man page for light on make install

Makefile

 PREFIX=$(DESTDIR)/usr
 BINDIR=$(PREFIX)/bin
+MANDIR=/usr/share/man/man1
 
 CC=gcc
 CFLAGS=-std=c89 -O2 -pedantic -Wall -I"./include"
+MANFLAGS=-h -h -v -V
 
 all:
 	$(CC) $(CFLAGS) -g -o light src/helpers.c src/light.c src/main.c
 exp:
 	$(CC) $(CFLAGS) -E  src/helpers.c src/light.c
+man:
+	help2man $(MANFLAGS) ./light | gzip - > light.1.gz
 
-install: all
+install: all man
 	mkdir -p $(BINDIR)
 	cp -f ./light $(BINDIR)/light
 	chown root $(BINDIR)/light
 	chmod 4755 $(BINDIR)/light
+	mkdir -p $(MANDIR)
+	mv light.1.gz $(MANDIR)
 
 uninstall:
 	rm $(BINDIR)/light
 	rm -rf /etc/light
+	rm $(MANDIR)/light.1.gz
 
 clean:
-	rm -vfr *~ light
+	rm -vfr *~ light light.1.gz