update free cmd output format

The printf output format bit is too few. Now it's 11 bits. There are many positions in other languages. Then the default is to fill in spaces. If you use Chinese translation, there is no place to fill in spaces. I can change it to 12 to ensure that there is one space.

This causes some other programs to use the free command to have unexpected results, like： https://github.com/KittyKatt/screenFetch/pull/722

I'm not sure if this is a problem, but I still submitted this PR. if you think it has nothing to do with the free command, please ignore this PR.

Thanks.