Documentation for atomic max and min do not define endienness

The documentation for `FDB_MUTATION_TYPE_MAX` says:

```
.. |atomic-max1| replace::
Sets the value in the database to the larger of the existing value and ``param``. If the existing value in the database is not present or shorter than ``param``, it is first extended to the length of
``param`` with zero bytes. If ``param`` is shorter than the existing value in the database, the
existing value is truncated to match the length of ``param``.
```

This is, however, not clear as it doesn't define whether it interpret the unsigned integer as little or big endian. I would make a PR to change this but I actually am not sure which one of the two it is :)