Add truncate warning to body of comment

[peter-evans]

Follows https://github.com/peter-evans/create-or-update-comment/pull/271

[github-actions[bot]]

This is a multi-line test comment

• With GitHub Markdown :sparkles:
• Created by create-or-update-comment

Edit: Some additional info

[github-actions[bot]]

This is a multi-line test comment

• With GitHub Markdown :sparkles:
• Created by create-or-update-comment

Edit: Some additional info

[github-actions[bot]]

This is a multi-line test comment read from a file. This is the second line. This is still the second line.

[github-actions[bot]]

This is a multi-line test comment read from a file. This is the second line. This is still the second line.