corporate proxies docs code example invalid in v1.12

[fsgh42]

https://docs.siderolabs.com/talos/v1.12/networking/corporate-proxies#configuring-a-machine-to-use-the-proxy

I think with v1.12 the example code there is outdated - name- and timeservers have their own, separate manifests now:

• https://docs.siderolabs.com/talos/v1.12/reference/configuration/network/resolverconfig
• https://docs.siderolabs.com/talos/v1.12/reference/configuration/network/timesyncconfig