docs(microservices): add note on using AsyncMicroserviceOptions

[raeisimv]

This update clarifies the use of AsyncMicroserviceOptions for configuring microservices dynamically using the ConfigService when the injection context is available post-instantiation. The addition addresses scenarios requiring flexible configuration setup.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/docs.nestjs.com/blob/master/CONTRIBUTING.md

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Docs
• Other... Please describe:

What is the current behavior?

Issue Number:

• feat: allow for microservice options to come from the di container nest#12622

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

It is a long-standing question on StackOverflow that has been flagged for a solution, but the respective solution or explanation is absent in the official NestJS documentation. https://stackoverflow.com/questions/66605392