sysv-generator: advertise the man page

src/sysv-generator/sysv-generator.c

@@ -151,6 +151,7 @@ static int generate_unit_file(SysvStub *s) {
         fprintf(f,
                 "# Automatically generated by systemd-sysv-generator\n\n"
                 "[Unit]\n"
+                "Documentation=man:systemd-sysv-generator(8)\n"
                 "SourcePath=%s\n"
                 "Description=%s\n",
                 s->path, s->description);