Add link to help in CD48 disconnect popup

[CrosRoad95]

Is your feature request related to a problem? Please describe.

most people don't know how to fix it, it says file can't be open, but why? even i'm not sure what went wrong.
People suggest to remove resources folder and it sometimes help

Describe the solution you'd like

add link to help, maybe try to fix this this issue, maybe file can be opened with read only access what prevent from failing when file is opened in other program

Describe alternatives you've considered

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Additional context

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Security Policy

• I have read and understood the Security Policy and this issue is not about a cheat or security vulnerability.

[Pirulax]

Probably related to #1340
Presumably the http downloader in netc doesn't close some handles properly.
Solution could be to move the downloader out of netc, and use a better-suited library instead of a simple curl.
Issue is that large files are re-downloaded even for small changes (like .img achieves).