Fix typos in miscinit.c.
Commit
f13ea95f9e moved the description of postmaster.pid file contents
from miscadmin.h to pidfile.h, but missed to update the comments in
miscinit.c.
Author: Hadi Moshayedi
Reviewed-by: Amit Kapila
Backpatch-through: 10
Discussion: https://postgr.es/m/CAK=1=WpYEM9x3LGkaxgXaxeYQjnkdW8XLsxrYRTE2Gq-H83FMw@mail.gmail.com