Update 03-commands.md, remove useless period

[SergeCroise]

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 5a0554b:

Number of broken URLs: 2

URL,RESULT,FILENAME
 http://untroubled.org/bcron/,failed,guides/automation/cronie.md
 https://www.linode.com/docs/guides/beginners-guide-to-lxd-reverse-proxy,failed,guides/containers/lxd_web_servers.md