plugins/sql: make testing-only sqlfilename option dev-sqlfilename.

dev options don't need to be documented, and this is only for debugging
the plugin itself.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/sql.c

@@ -1614,7 +1614,7 @@ int main(int argc, char *argv[])
 	}
 	plugin_main(argv, init, PLUGIN_RESTARTABLE, true, NULL, commands, ARRAY_SIZE(commands),
 	            NULL, 0, NULL, 0, NULL, 0,
-		    plugin_option("sqlfilename",
+		    plugin_option("dev-sqlfilename",
 				  "string",
 				  "Use on-disk sqlite3 file instead of in memory (e.g. debugging)",
 				  charp_option, &dbfilename),