Update windows_exporter reference
Prometheus exporter for hardware and OS metrics exposed by \*NIX kernels, written
in Go with pluggable metric collectors.
-The [WMI exporter](https://github.com/martinlindhe/wmi_exporter) is recommended for Windows users.
+The [Windows exporter](https://github.com/prometheus-community/windows_exporter) is recommended for Windows users.
To expose NVIDIA GPU metrics, [prometheus-dcgm
](https://github.com/NVIDIA/gpu-monitoring-tools/tree/master/exporters/prometheus-dcgm)
can be used.
