docs: clarify alert behavior for non-existent mount points (#22038)
* docs: clarify alert behavior for non-existent mount points Add guidance explaining that alerts based on chart labels require the underlying chart to exist. Disk space alerts won't trigger for mount points that don't exist (e.g., CIFS mount failures after reboot). Suggests alternative approaches: systemd mount unit monitoring and filecheck collector for monitoring mount failures. * docs: add Useful resources section to disk_space_usage guide Add links to relevant documentation for disk space monitoring: - Netdata disk space collector documentation - Linux disk usage commands guide - systemd mount unit troubleshooting for mount failures * docs: remove unnecessary Useful resources section from disk_space_usage guide * docs: add Useful resources section with CTA links to disk_space_usage.md * docs: replace plain bullet points with CTA links in REFERENCE.md chart labels admonition * docs: use clean CTA links in disk_space_usage Useful resources section * docs: use CTA links in REFERENCE.md chart labels admonition * docs: replace internal /src/ links with external URLs in disk space and REFERENCE guides * docs: remove external link from alert chart labels note * docs: add Collectors overview link to chart labels admonition * Remove vague external links from health guides Per reviewer feedback: - Both files are not on Learn (not in docs/.map/map.yaml) - External CTA links (Red Hat guide, freedesktop.org) are vague and not specific - Removed Useful resources sections since no useful internal link candidates exist * docs: remove link from chart labels important note Remove the Collectors overview link from the alert chart labels :::important block in REFERENCE.md. The block's content explaining that CIFS mount failures prevent disk.space chart creation already satisfies the guidance; the link violated the no-links acceptance criteria. Fixes feedback: links to non-Learn files should not be added. * Apply suggestions from code review Co-authored-by: Fotis Voutsas <fotis@netdata.cloud> * Update REFERENCE.md * Apply suggestions from code review Co-authored-by: Fotis Voutsas <fotis@netdata.cloud> --------- Co-authored-by: nedi-app[bot] <bot@netdata.cloud> Co-authored-by: Fotis Voutsas <fotis@netdata.cloud>