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 的开头说明和 issue 模板，然后检查 DPO 和 triager 指导内容是在何处引入的。明确说明 contributors 应在 triager 验证后再打开 PR，同时指出围绕明确 bug 的讨论。只要 issue-to-PR 工作流和例外情况对 contributors 都有明确说明，就算完成。