Change default gender in the dining philosophers project

The paper from which this example was taken made the mistake of assuming
that all five philosophers are men. This is a hypothetical
example--there are no actual philosophers eating spaghetti--so there is
no good reason to make this assumption. Since women make up about half
of the human population, all things being equal, women should represent
about half of the philosophers. However, because this mistake has stood
since 1985, I have changed *all* of the pronouns to be female, to make
up for lost time. If someone would like to revert this patch or switch
to neutral pronouns after 30 years, feel free to set your alarm clock
for 2045.

Author: sferik

src/doc/trpl/dining-philosophers.md

@@ -7,20 +7,20 @@ called ‘the dining philosophers’. It was originally conceived by Dijkstra in
 [paper]: http://www.usingcsp.com/cspbook.pdf
 
 > In ancient times, a wealthy philanthropist endowed a College to accommodate
-> five eminent philosophers. Each philosopher had a room in which he could
-> engage in his professional activity of thinking; there was also a common
+> five eminent philosophers. Each philosopher had a room in which she could
+> engage in her professional activity of thinking; there was also a common
 > dining room, furnished with a circular table, surrounded by five chairs, each
 > labelled by the name of the philosopher who was to sit in it. They sat
 > anticlockwise around the table. To the left of each philosopher there was
 > laid a golden fork, and in the centre stood a large bowl of spaghetti, which
-> was constantly replenished. A philosopher was expected to spend most of his
-> time thinking; but when he felt hungry, he went to the dining room, sat down
-> in his own chair, picked up his own fork on his left, and plunged it into the
+> was constantly replenished. A philosopher was expected to spend most of her
+> time thinking; but when she felt hungry, she went to the dining room, sat down
+> in her own chair, picked up her own fork on her left, and plunged it into the
 > spaghetti. But such is the tangled nature of spaghetti that a second fork is
 > required to carry it to the mouth. The philosopher therefore had also to pick
-> up the fork on his right. When he was finished he would put down both his
-> forks, get up from his chair, and continue thinking. Of course, a fork can be
-> used by only one philosopher at a time. If the other philosopher wants it, he
+> up the fork on her right. When she was finished she would put down both her
+> forks, get up from her chair, and continue thinking. Of course, a fork can be
+> used by only one philosopher at a time. If the other philosopher wants it, she
 > just has to wait until the fork is available again.
 
 This classic problem shows off a few different elements of concurrency. The