DOC: argmin, argmax, argort, etc. should link to `np.take_along_axis` in their documentation

In #6075, I wondered whether it might be possible to

to have some simple way to use the output of np.arg[min|max|sort] as a proper index (to avoid hackery as in https://github.com/astropy/astropy/blob/master/astropy/time/core.py#L896 – if there is a simpler way already, let me know!)

and @jaimefrio suggested that it might be simpler to have

a make_me_an_indexing_tuple=False new keyword argument for the argxxx functions?

That indeed seems better, so I’m raising this as a separate issue. The code linked to above could be used as a template on how to generate the index tuple.

[ElieGouzien]

I think it would be lot better than today’s implementation if the axis=None option returned something equivalent to :

np.unravel_index(np.argsort(a, axis=None), a.shape)

[seberg]

I think this issue is now irrelevant, since we have np.take_along_axis instead, which solves the issue. I will however transform it into a Documentation issue, since those functions should list it under the See Also section at least.