Improve docs. Add examples. Fix typos.

README.md

docs/development.md

docs/logic.md

example/redisfailover/all-options.yaml

example/redisfailover/basic.yaml

example/redisfailover/custom-config.yaml

example/redisfailover/custom-shutdown.yaml

...ple/redisfailover/persistent-storage-no-pvc-deletion.yaml

example/redisfailover/persistent-storage.yaml