docs(config): expand example pyroscope.yaml with documented defaults

[alliasgher]

The cmd/pyroscope/pyroscope.yaml file contained only a single uncommented line. This expands it with the most commonly configured sections (server, storage, target, log level, multi-tenancy, memberlist, limits, self-profiling), with inline comments explaining each option and a link to the full reference documentation.

Fixes #3835

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Note

Medium Risk
Although primarily documentation, this file is copied into the Docker image as the default config, so newly explicit settings (notably storage.path and listen addresses/ports) could alter out-of-the-box runtime behavior if they differ from compiled defaults.

Overview
Updates cmd/pyroscope/pyroscope.yaml from a single setting to a fully commented example configuration, linking to the reference docs and describing common knobs.

It now explicitly sets defaults for server (HTTP bind/port and gRPC port) and storage.path, and includes commented-out templates for target, log_level, multitenancy_enabled, memberlist, limits, and self_profiling to guide typical deployments.

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[simonswine]

Thanks @alliasgher I like this idea ❤️

My thinking was this needs to be a bit more automated, wdyt about #5151

[simonswine]

I am closing this as #5151 has merged now let me know, if there is anything missing you would like to see