Improve windowed "max" documentation

[artemik]

Please describe the feature request.
I'd like Micrometer docs to explain more about time windowed "max" values.

Rationale
Previously, there was ticket (#1587) about confusion around it which led to this improvement: micrometer-metrics/micrometer-docs#101. However, the current explanation in Micrometer docs (in here https://docs.micrometer.io/micrometer/reference/concepts/distribution-summaries.html) is confusing for me as an end user, because it's not clear what it practically means, sounds more like implementation detail, and is buried quite deep (regardless of it being highlighted with a "Note" box).

Practically, currently I see Spring Boot outputs the following metrics:

• http.server.requests histogram (who has "max");
• http.server.requests.max gauge.

It's not easily clear which one means what and why there are two. For example, in Grafana I just see one of them, because probably one overrides the other.

It would be great if docs provided practical example (something like saying "for example in Spring, http.server.requests.max is a time windowed max...").

As I understand, Micrometer doesn't specify an exact list of metrics with their meanings (unlike OpenTelemetry), so because it's Spring who actually outputs those, it could be more issue of Spring docs that don't explain it (currently, doesn't explain anything besides the name: https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#actuator.metrics.supported.spring-mvc), so let me know if you think it's an issue for them instead, but since Micrometer mentioned already windowed max in the docs, since it provides reference implementation for some other components, and since the end goal is making it clear for users anyway, it could be worth explaining in Micrometer docs.