Merge branch '5963-fix-reference-to-the-old-documentation-in-upgrade-md-and-readme-md' into '1.3-dev'

Resolve "fix reference to the old documentation in UPGRADE.md and README.md"

See merge request fusiondirectory/fd!549

(cherry picked from commit 245569a8)

09c75042 🚑 fix(documentation) fix reference to the old documentation in UPGRADE.md and README.md