Clarify content privacy in the privacy policy

[dandv]

https://jsonlint.com/privacy doesn't say anything about the content that is linted. This can easily include API keys or PII.

[toddynho]

@dandv I can tell you that we don't save, or have a mechanism to save, or storage of any kind associated with the source code you can see in the repo here. We don't have intent to ever save anything. I do need to check vercel log retention to see what may be saved there and for what period of time before closing this out.