Add warning about only loading .spydata files from trusted sources

[CAM-Gerlach]

Pull Request

Pull Request Checklist

• [x] Read and followed this repo's Contributing Guidelines
• [x] Based your PR on the latest version of the correct branch (master or 4.x)
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• [x] Described your changes and the motivation for them below
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Description of Changes

Adds a warning to remind users to not load .spydata data unless they created it themselves, or they verifiably trust its source, since it inherently runs untrusted code.

Issue(s) Resolved

Fixes #328

[CAM-Gerlach]

Yeah, I'm not super solid on that particular word either—any alternate suggestions? Or, should I just elide it?

[jitseniesen]

I would remove it, but if you feel it should be stronger than just "trust", how about "fully trust" or "completely trust"?

[CAM-Gerlach]

Yeah, my intent there was to emphasize that users should not only think they trust it, but also verify that they did so—the old "trust but verify" (since users may implicitly trust that, e.g., an email came from a close college, when it in fact was phishing, spoofing, a hacked account, etc). But I'm not sure that comes across clearly. In any case, I changed it to "fully" :+1: .