Add documentation about the combined use of $globals and $runtime_params

[noklam]

Description

Read #2531 for the full context.

There are many questions asked in the slack such as "how to override global with runtime parameters", we explicitly block this but we don't have the reason document.

The docs should document 2 things:

1. The rationale of the design, WHY we block this
2. How to do this in the preferred way (nested globals{xxx, {$runtime_param}))

Documentation page (if applicable)

• https://docs.kedro.org/en/latest/configuration/advanced_configuration.html
• FAQ

(Try to search from the console see if you can find the section easily with keywords)

Possible solution

Summary #2531, the discussion was mostly documented already in the issue, we just need to make that available in docs.

[datajoely]

Another user touching this question

[noklam]

Make sure to read #2531 for the discussion.