linking externally to the latest branch

[Trevor Woerner <twoerner@gmail.com>]

Hi,

The Mender documentation links into the Yocto Project documentation to allow
users an easy path for performing additional research as they work through
the Mender documentation while working on getting Mender working in the Yocto
builds. Many of those links (from Mender's docs) link to the Yocto Project's
old docs site, so I was thinking of updating some of those links. However,
Mender only officially supports Dunfell (3.1.x) with their free offering,
so when a user clicks on the old links they are forwarded to the new Yocto
Project documentation, referencing the "latest" docs release. This will
inevitably confuse users since Mender is based on Dunfell, not master.

The Yocto Project's documentation site conveniently provides a drop-down which
allows users to switch to the documentation for a given release, but these
releases are specific to the exact point release of a given branch.

For example to link to the Dunfell documentation regarding read-only rootfs I
could update the link on:
	https://docs.mender.io/system-updates-yocto-project/image-customization/read-only-root-filesystem
which currently points to:
	https://www.yoctoproject.org/docs/latest/mega-manual/mega-manual.html#creating-a-read-only-root-filesystem?target=_blank
to point to:
	https://docs.yoctoproject.org/3.1.12/singleindex.html#creating-a-read-only-root-filesystem
but that's specific to 3.1.12 exactly.

Is there a way to replace the "3.1.12" in the above URL with something that
means "the latest 3.1.x"?

Best regards,
	Trevor