add to rockydocs_formatting.md a note about anchors

[sspencerwire]

• anchors are a link type that should be avoided

Author checklist (Completed by original Author)

• Good fit for the Rocky Linux project? Title and Author Metatags inserted ?
• If applicable, steps and instructions have been tested to work
• Initial self-review to fix basic typos and grammar completed

Rocky Documentation checklist (Completed by Rocky team)

• 1st Pass (Document is good fit for project and author checklist completed)
• 2nd Pass (Technical Review - check for technical correctness)
• 3rd Pass (Detailed Editorial Review and Peer Review)
• Final approval (Final Review)

[github-actions]

Test results for e340a9b:

Number of broken URLs: 7

URL,RESULT,FILENAME
 http://example.org/foo.txt,failed,books/web_services/052-load-balancer-proxies-varnish.md
 https://azuremarketplace.microsoft.com/en-us/marketplace/apps/resf.rockylinux-aarch64,failed,guides/cloud/migration-to-new-azure-images.md
 https://www.volted.net/,failed,guides/contribute/README.md
 http://laurenzkruty.de,failed,guides/contribute/README.md
 http://0.0.0.0:61208/,failed,guides/network/glances_network_monitoring.md
 https://your.domain.name/install.php,failed,guides/cms/chyrp_lite.md
 https://www.landoflinux.com/linux_procfs_sysfs.html,failed,gemstones/core/view_kernel_conf.md