[docs/collector] Document recommendations regarding rate limiting and load balancing

[mx-psi]

Desired feature or idea: The Collector SIG wants to encourage users to rely on existing solutions for rate limiting and load balancing. We want to document this and link to best practices docs to make sure this is covered.

Additional context: Part of the discussion in open-telemetry/opentelemetry-collector#11499, see https://docs.google.com/document/d/1BO7hMg0K7zFQ0219z61yRj-2JMMTW_HfoX3Vt6kXW8E/edit?disco=AAABUC8iXkg