Add Linux dashboard

[cyrille-leclerc]

Changes

Inspired by https://grafana.com/grafana/dashboards/20376-opentelemetry-collector-hostmetrics-node-exporter/

Merge Requirements

For new features contributions, please make sure you have completed the following
essential items:

• CHANGELOG.md updated to document new feature additions
• Appropriate documentation updates in the docs
• Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure
which docs need to be changed ping the
@open-telemetry/demo-approvers.

[julianocosta89]

@cyrille-leclerc is this one missing anything, or is it ready for review?

[cyrille-leclerc]

Thanks for reaching out. I would like to report with finer granularity of the file system usage but it could be a subsequent milestone.

[cyrille-leclerc]

@julianocosta89 ready for review.