disable valkey persistence by default, but add some more docs on where you can find the parameters for each chart to enable it if you want

[jessebot]

• disables valkey persistence by default, as we don't want that for the ci pipeline testing because it makes cleanup harder
• This is a bit of a compromise on fix(readme) document additional information about storage #5 by adding docs to the root level README.md on where you can find the subchart docs