feat(alert): adding sample prometheus rules for ZFSPV

[pawanpraka1]

This PR has a sample rule to monitor the volume space utilization, and once available space is less than 10%, it will start firing the alert.

 100 * kubelet_volume_stats_available_bytes{job="kubelet"}
          /
        kubelet_volume_stats_capacity_bytes{job="kubelet"}
          < 10

Just update the yaml with the desired alert rule and apply the yaml. You will start getting the alert as per set rule.

Signed-off-by: Pawan pawan@mayadata.io

[codecov-io]

Codecov Report

Merging #32 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #32   +/-   ##
=======================================
  Coverage   83.33%   83.33%           
=======================================
  Files           1        1           
  Lines          72       72           
=======================================
  Hits           60       60           
  Misses         12       12

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[kmova]

Thank you @pawanpraka1