Invalid link to Percona docs

[Robert Krátký]

Where: https://docs.openstack.org/charm-guide/latest/admin/upgrades/openstack.html#percona-cluster

The link to *Percona strict mode* is invalid.

Wrong: https://www.percona.com/doc/percona-xtradb-cluster/LATEST/features/pxc-strict-mode.html
Right: https://docs.percona.com/percona-xtradb-cluster/LATEST/strict-mode.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-guide/+/901557

[Peter Matulis (petermatulis)]

Thanks Robert. There is an old PR around for fixing this [0]. It's actually not that straightforward as it depends what the user is upgrading to. What database software is used depends on what the underlying Ubuntu version is involved (Bionic or Focal), which alters the steps needed to upgrade. So at a higher level, some extra guidance may be needed here. I'll look into this.

[0]: https://review.opendev.org/c/openstack/charm-guide/+/895695

[Robert Krátký (rkratky)]

Thanks for the background. Feel free to discard my PR. But I'd suggest keeping this bug report and linking it to your Gerrit change, so that there's a paper trail in case others notice the bug, too.

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Peter Matulis <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/charm-guide/+/901557
Reason: Being handled in 0021d9294fe006e0b1ad6c135a12af2626fa5896