Add usage documentation for Monitor tab UI

[albertteoh]

Requirement - what kind of business use case are you trying to solve?

Relates to: jaegertracing/jaeger#2954

Write documentation for the ATM feature in Jaeger including:

• Configuration for both backend and frontend components
• Architecture
• API specification
• UI features and usage

Any open questions to address

• I propose to mark the ATM feature as experimental to give it some time to stabilise as users test it.

• Should all documentation reside in a single page, similar to the Jaeger Operator docs, or should they be spread out amongst the respective Frontend/UI (how to enable the Monitor tab, its features and usage), Architecture (the required components to make it work) and APIs (API specification) pages?

  It's worth noting that ATM-related docs already exist in CLI Flags.

[yurishkuro]

Discussed this at project call, it seems it's worth doing a single feature-oriented docs page for this, but also duplicate some info where necessary, e.g. in the UI config sections.

[albertteoh]

Great, thanks for raising it on the call and for the update, @yurishkuro! 🙏🏼