PXC-4715 [DOCS] Fix broken links in PXC doc project (8.0)

[alina-derkach-oaza]

modified:   docs/add-node.md
modified:   docs/apt.md
modified:   docs/bootstrap.md
modified:   docs/clone-sst.md
modified:   docs/configure-cluster-rhel.md
modified:   docs/configure-cluster-ubuntu.md
modified:   docs/configure-nodes.md
modified:   docs/crash-recovery.md
modified:   docs/encrypt-traffic.md
modified:   docs/failover.md
modified:   docs/garbd-howto.md
modified:   docs/get-started-cluster.md
modified:   docs/glossary.md
modified:   docs/index.md
modified:   docs/install-index.md
modified:   docs/install-pro.md
modified:   docs/load-balance-proxysql.md
modified:   docs/nbo.md
modified:   docs/pro-files.md
modified:   docs/release-notes/8.0.31-23.md
modified:   docs/release-notes/8.0.34-26.md
modified:   docs/release-notes/Percona-XtraDB-Cluster-8.0.25-15.1.md
modified:   docs/restarting-nodes.md
modified:   docs/secure-network.md
modified:   docs/security-index.md
modified:   docs/set-up-3nodes-ec2.md
modified:   docs/state-snapshot-transfer.md
modified:   docs/strict-mode.md
modified:   docs/upgrade-guide.md
modified:   docs/verify-replication.md
modified:   docs/virtual-sandbox.md
modified:   docs/wsrep-files-index.md
modified:   docs/wsrep-provider-index.md
modified:   docs/wsrep-status-index.md
modified:   docs/wsrep-system-index.md
modified:   docs/xtrabackup-sst.md
modified:   docs/yum.md

[patrickbirch]

ok