Add upgrade note for v.58

Merge pull request pi-hole#837 from pi-hole/dev

Release 5.8 - "Third time's the charm" edition

Merge pull request pi-hole#797 from pi-hole/dev

Dev -> master

Merge pull request pi-hole#776 from pi-hole/dev

v5.6 Release

Merge pull request pi-hole#765 from pi-hole/dev

Release 5.5

Merge pull request pi-hole#765 from pi-hole/dev

Release 5.5

Merge pull request pi-hole#760 from pi-hole/fix/latest-tag

Use Location: header for GitHub API call for latest tag detection.

Merge pull request pi-hole#741 from pi-hole/dev

v5.2.2 and various to master

Merge pull request pi-hole#741 from pi-hole/dev

v5.2.2 and various to master

Merge pull request pi-hole#717 from pi-hole/dev

Dev to Master [5.2.1]