Clarify issue/PR choreography

From a discussion with @picnixz:

I think the problem with the devguide is the first sentence is "Create an issue that describes the change" and you'll see the mention to DPO only during creation. We can improve that
I would expect people to read the issue template correctly and understand that something is not trivial
and more importantly: WAIT for triagers to decide whether it's ok or not as an issue
There are obvious cases where the issue doesn't a triager for validation, like a clear bug (and even this is subject to interpretation sometimes) but the process issue+PR is the worst for triagers, especially when the PR is automated.

This might be a duplicate of other feedback here in issues, but I wanted to capture it before going back to $WORK.

首先定位 devguide 的開頭說明和 issue 範本，然後檢查 DPO 和 triager 指引內容是在何處引入的。明確說明 contributors 應在 triager 驗證後再開啟 PR，同時指出圍繞明確 bug 的討論。只要 issue-to-PR 工作流程和例外情況對 contributors 都有明確說明，就算完成。