[chore][processor/dynamic_sampling] expand documentation for alpha

[MikeGoldsmith]

Description

Closes out the documentation items on the alpha tracking issue:

• The "How it works" section now states explicitly that samplers only ever produce rates and that the keep/drop decision is a single mechanism for every sampler type, the processor's rate-to-threshold conversion checked against the trace's randomness. A note contrasts this with dynsampler-go's own samplers (e.g. its DeterministicSampler hash check), which this processor never uses.
• A new "Worked examples" section with two complete configurations: error retention with an adaptive default rule, and a throughput-bounded fleet, each with sizing guidance.

Docs only, no behavior change.

Link to tracking issue

Refs #49311

Testing

The OTTL condition used in the worked examples is covered by the existing README example compile test. Full test suite and lint pass.

Documentation

This PR is documentation.

Authorship

• I, a human, wrote this pull request description myself.

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Pull request dashboard status

Merged · refreshed 2026-08-04 22:32 UTC

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