Modify see also links in existing .md files to php

[Fangcong-Yin]

so that they can be rendered on the open mpi website
Signed-off-by: Fangcong Yin fyin2@nd.edu

[ompiteam-bot]

Can one of the admins verify this patch?

[jsquyres]

ok to test

[jsquyres]

This is for an upcoming change on ompi-www so that it will render the Markdown man pages.

Let's hold off on merging this PR until we have the matching PR on the ompi-www side ready to go.

[jsquyres]

All of this content ended up getting used, but as part of the larger convert-to-Sphinx-and-ReStructured-Text effort in #8329. I'm closing this PR without merging, but know that we used all of this work as part of the behind-the-scenes work in #8329.