[DOC]: Explain the choice of absolute/relative tolerance for check_less_precise in assert_almost_equal
The docstring in https://github.com/pandas-dev/pandas/blob/9e982e18678c47c83ce2bb5932f844e2d9ee21f3/pandas/util/testing.py#L226-L229 does not specify how the number of decimal digits is going to be used, yet https://github.com/pandas-dev/pandas/blob/9e982e18678c47c83ce2bb5932f844e2d9ee21f3/pandas/_libs/testing.pyx#L203-L210 switches between absolute and relative tolerance depending on the (hardcoded) magnitude on the number.