Doc sorting algos

[kshyatt]

No description provided.

[ChristianKurz]

Thanks for improving documentation!

I think it may be better to have the characteristics of a sorting function in a list/table:

`PartialQuickSort{T <: Union{Int,OrdinalRange}}`

Indicate that a sorting function should use the partial quick sort
algorithm, which is not stable.
Partial quick sort returns the smallest k elements sorted from smallest
to largest, finding them and sorting them using QuickSort.
A stable sort preserves the ordering of elements which
compare equal (e.g. "a" and "A" in a sort of letters which
ignores case). Partial quick sort can be performed in-place in memory.
Like MergeSort, it is a divide-and-conquer sort algorithm.

vs.

`PartialQuickSort{T <: Union{Int,OrdinalRange}}`

Indicate that a sorting function should use the partial quick sort algorithm.

Partial quick sort returns the smallest k elements sorted from smallest
to largest, finding them and sorting them using QuickSort.

Characteristics:

• not stable: Does not preserve the ordering of elements which
  compare equal (e.g. "a" and "A" in a sort of letters which
  ignores case).
• in place: Partial quick sort can be performed in-place in memory.
• divide-and-conquer

[kshyatt]

I could go either way on this one. Anyone else have thoughts?

[StefanKarpinski]

A list does seem a bit easier to compare at a glance.

[kshyatt]

Good to go?