Dnf package manager page added

[ShyRain]

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 aaf12ab:

Number of broken URLs: 5

URL,RESULT,FILENAME
 http://nextcloud.yourdomain.com/,failed,guides/cms/cloud_server_using_nextcloud.md
 https://www.yourdomain.com/,failed,guides/security/generating_ssl_keys_lets_encrypt.md
 https://www.qyecst.cn,failed,guides/contribute/README.md
 https://www.linode.com/docs/guides/beginners-guide-to-lxd-reverse-proxy,failed,guides/containers/lxd_web_servers.md
 https://www.ssi.gouv.fr/en/,failed,books/disa_stig/disa_stig_part2.md

[sspencerwire]

Next time, just remember the terminal output doesn't need to be an image. :-)