Add QNAP installation instructions

[moodyblue]

Create install instructions for QNAP NAS. Fixes #2371

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[moodyblue]

Link to Z2M site has been removed as required by the failing run.

[stefan-hoehn]

Please add a description to the PR and add the following to it:

Fixes #2371

[stefan-hoehn]

Obrigado, thanks for the contribution, see my comments on the text.

[moodyblue]

I've also added a new section "Manual Update"

[stefan-hoehn]

@kaikreuzer

While talking with @florian-h05 today we were wondering if we should document how a package that is not provided by us should be part of our documentation?

As the following is not our distro

See https://www.myqnap.org/product/openhab/

I wonder if the written documentation of @moodyblue shouldn't rather go there?

(sorry @moodyblue for the late insight)

[moodyblue]

I understand. While it's possible to install JDK17 in QNAP and perform a manual install using the official repo this is far more complex. But I can write such instructions if you prefer.

You may also notice that in the meantime I've added instructions to replace MyQNAP's distribution with your distribution, so there is always an option to "revert to oficial distriburion" while preserving the normal way that packages are executed in QNAP systems.

I'm Ok with any decision you make. Unfortunately it's not possible to document the installation with high detail in MyQNAP repo.

[moodyblue]

@stefan-hoehn @kaikreuzer Can you pls let me know what to do ?