Commit 3f6737f688
("doc: autopts: Remove duplication of getting started guide") removed
duplicated text by linking to the getting started guide.
However, the link format is not correct. It is using a link to the
latest upstream Zephyr getting started guide. This has two problems:
1. It will link to the wrong document when the autopts guide
is part of an official release documentation. For example,
the Zephyr 3.0 release documentation HTML page for these
docs will be linking to the main branch GSG, not the v3.0
getting started guide. This combination will not be correct
in general because dependencies change.
2. It breaks downstream distributions which bundle their own
versions of the Zephyr documentation as well, for similar
reasons.
The two documents are part of the same Sphinx docset, so the right way
to do this is with :ref. Fix it.
Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>