[prometheus-blackbox-exporter] ICMP: Suggest setting net.ipv4.ping_group_range in podSecurityContext

[fatz]

What this PR does / why we need it

To enable ICMP probes net.ipv4.ping_group_range must be set in some environments.

This PR adds a hint to the release notes aside of the hint to set securityContext.capabilities.add: ["NET_RAW"] for enabling ICMP.

This will IMO make it easier for users to get ICMP probes working

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer

Checklist

• DCO signed
• Chart Version bumped
• Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.

[monotek]

some text should be added why its needed and maybe in which environments.
also chart version needs to be updated.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.

[monotek]

chart version needs to be updated

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.