Add persistent_comment option for /describe

[hnoson]

The comment isn't replaced and there is no option to do it when publish_description_as_comment is enabled.

[mrT23]

its possible

why do you want to use at all the mode of 'publish_description_as_comment' for describe ?

[hnoson]

since we update the description manually and it's sometimes overwritten by the generated one

[mrT23]

unclear

What's your use case for using publish_description_as_comment at all ? why not write directly to the PR header ?
It does not overwrite the original content, it adds to it:

https://pr-agent-docs.codium.ai/usage-guide/automations_and_usage/#github-app-automatic-tools-when-a-new-pr-is-opened

[hnoson]

1. Open a PR
2. Start editing the description manually
3. PR-Agent generates content based on the content before editing
4. Finish editing manually
5. The manual edit or PR-Agent overwrites content of the other

To avoid this issue, we enabled publish_description_as_comment

[mrT23]

#837
done

[hnoson]

Thanks!