Update certificates docs for mono and nuget

[viceice]

mono has it's own cert store which needs to be updated with cert-sync (automatically done by update-ca-certificates, mono must be installed).

so we need to update docs/custom-root-ca.md with that information

Hopefully the old boringssl get's replaced soon and it will be possible to use the usual ca-certifactes store on linux some day.

• https://gitlab.winehq.org/mono/mono/-/releases/mono-6.14.0#update-cryptography

• Add support for new tool Mono #5806

• Add support for new tool NuGet CLI #5807