Update 02-advanced.md - debug module

[DavisBarnabas]

The var attribute in debug module doesnt require "{{ }}" as it runs in Jinja2 context and has an implicit {{ }} wrapping. Removed the wrapping "{{ }}" as it will throw 'template error while templating string'.

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 803340e:

Number of broken URLs: 2

URL,RESULT,FILENAME
 https://mirror2.sandyriver.net/pub/rocky/8.8/PowerTools/x86_64/os/,failed,books/admin_guide/13-softwares.md
 https://rsnapshot.org/download.html,failed,guides/backup/rsnapshot_backup.md

[sspencerwire]

Thanks for the correction!

[sspencerwire]

@all-contributors add @DavisBarnabas for content

[allcontributors]

@sspencerwire

I've put up a pull request to add @DavisBarnabas! 🎉