#10960: fix 'stat' links, link to lstat from stat, general tidy of stat doc.

#10960: fix 'stat' links, link to lstat from stat, general tidy of stat doc.

Original patch by Michal Nowikowski, with some additions and wording
fixes by me.

I changed the wording from 'Performs a stat system call' to 'Performs
the equivalent of a stat system call', since on Windows there are no
stat/lstat system calls involved.  I also extended Michal's breakout
of the attributes into a list to the other paragraphs, and rearranged
the order of the paragraphs in the 'stat' docs to make it flow
better and put it in what I think is a more logical/useful order.