[admin] Make issue template comments actual markdown comments

[learn-build-service-prod[bot]]

Learn Build status updates of commit 1ee1509:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
.github/ISSUE_TEMPLATE/1_documentation-issue.md	:white_check_mark:Succeeded
.github/ISSUE_TEMPLATE/2_sample-request.md	:white_check_mark:Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel