change notes to see "Implementation Notes" to xref to std-notes;
add xref to std-notes to getrlimit, setrlimit;
add note to document limitations of getrlimit, setrlimit resources support
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 winsup/doc/posix.xml | 101 ++++++++++++++++++++++++-------------------
 1 file changed, 57 insertions(+), 44 deletions(-)