docker.md: Remove stray newlines and simplify sentences

[neelchauhan]

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 6fbdb74:

Number of broken URLs: 4

URL,RESULT,FILENAME
 https://azure.microsoft.com/en-us/,failed,guides/automation/templates-automation-packer-vsphere.md
 https://www.linode.com/docs/guides/beginners-guide-to-lxd-reverse-proxy,failed,guides/containers/lxd_web_servers.md
 https://csrc.nist.gov/publications/detail/sp/800-171/rev-2/final,failed,books/disa_stig/disa_stig_part2.md
 https://csrc.nist.gov/projects/security-content-automation-protocol,failed,books/disa_stig/disa_stig_part2.md

[wsoyinka]

Thank you @neelchauhan :-)