DOC: The axis argument of average can be a tuple of ints

[cancan101]

Closes #8604

[charris]

Should be a single paragraph, i.e., combined with preceding line. I'd cut and paste from the corresponding part of the sum docstring with relevant changes to have a more complete explanation.

[charris]

I think the .. versionadded:: found in sum would also be correct here. I'd feel happier if this functionality was tested :(

[cancan101]

I copied this from:

numpy/numpy/core/fromnumeric.py

Lines 2803 to 2810 in eefc4b8

	axis : None or int or tuple of ints, optional
	Axis or axes along which the means are computed. The default is to
	compute the mean of the flattened array.
	.. versionadded:: 1.7.0
	If this is a tuple of ints, a mean is performed over multiple axes,
	instead of a single axis or all the axes as before.

.

Do you like the mean formatting or the sum formatting?

I wasn't sure of what version added to use. I can use .. versionadded:: 1.7.0 if you want.

[charris]

I think that version is probably correct as the functionality seems more inherited than intentional. The sum docs seem a bit better to me with regard to the tuple.

[charris]

See doc/source/def/gitwash/development_workflow.rst for guidelines on commit message formatting.

[cancan101]

fixed

[charris]

Thanks @cancan101 .