Automatically add labels to issue when they are raised from MDN

[Rumyra]

When issues are raised via the 'Report a problem with this content' link on MDN, we have information about where the issue is coming from, plus it's a new issue.

Labels should be:

• Which area of content is applicable, such as Content: CSS - this can be derived from the URL, even if it's not a perfect science it's a good start for issue triagers
• needs-triage label - currently we are adding these manually so issue triagers can seach via this label, automatically adding this would save this work

[peterbe]

Doesn't it already do that? This is what I see after having clicked that "Report a problem with this content" link.

[Rumyra]

So looking into this it would be good to check through what's being added, some issues are coming through with no labels - maybe this is 'check auto issue labelling'

[schalkneethling]

As we have needs-triage automatically added, we are good here for now.