Update xo-lite.md - ssl cert configuration

[redy01]

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[redy01]

ssl cert configuration

[stormi]

It's a good idea to add a word about TLS certificates, but the method described is not appropriate. This must be done using XAPI methods.

Ideally, we'd just link towards a more general section about TLS certificates in XCP-ng (we have https://docs.xcp-ng.org/guides/TLS-certificates-xcpng/ that we need to improve)