docs: add missing uv.os_unsetenv() parameter

[notomo]

uv.os_unsetenv takes a name parameter.

📝 code

luv/src/misc.c

Lines 498 to 506 in 8ca04df

	static int luv_os_unsetenv(lua_State* L) {
	const char* name = luaL_checkstring(L, 1);
	int ret = uv_os_unsetenv(name);
	if (ret == 0)
	lua_pushboolean(L, 1);
	else
	return luv_error(L, ret);
	return 1;
	}

[zhaozg]

Thanks