Editorial: Add notice on the _or condition depth.

[yoshisatoyanagisawa]

In WICG/service-worker-static-routing-api#5 and WICG/service-worker-static-routing-api#6, it was suggested to limit the number of conditions in the or condition syntax, and depth of nested and/or conditions.

This PR adds notice on such limitations.

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[yoshisatoyanagisawa]

@domenic Can I ask you to review?
@sisidovski @azaika I hope this covers what you meant in the github issues. I tried to avoid specific numbers because I wanted to give some flexibility on the way browsers implement this.

[mkruisselbrink]

It probably would be good to have a (normative) requirement for the minimum nesting level that browser should support? (with corresponding WPT tests)

[yoshisatoyanagisawa]

It probably would be good to have a (normative) requirement for the minimum nesting level that browser should support? (with corresponding WPT tests)

If my put myself in the web developers shoes, it is understandable. They should want to know the depth that works on all browsers.

We currently have https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/web_tests/external/wpt/service-workers/service-worker/tentative/static-router/resources/router-rules.js;l=76;drc=bc4f2163da44000fc411e6aeff490f19c414b495 for the nested conditions. I do not come up with the case more nests are needed.

Let me add such tests to not, and revisit here.