Add README for adaptive sampling

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.82%. Comparing base (9bdd368) to head (72a2545). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5955 +/- ## ======================================= Coverage 96.82% 96.82% ======================================= Files 345 345 Lines 16518 16518 ======================================= Hits 15993 15993 Misses 339 339 Partials 186 186 ``` | [Flag](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | Coverage Δ | | |---|---|---| | [badger_v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `8.03% <ø> (ø)` | | | [badger_v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.82% <ø> (ø)` | | | [cassandra-3.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `16.62% <ø> (ø)` | | | [cassandra-3.x-v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.75% <ø> (ø)` | | | [cassandra-4.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `16.62% <ø> (ø)` | | | [cassandra-4.x-v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.75% <ø> (ø)` | | | [elasticsearch-6.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `18.79% <ø> (ø)` | | | [elasticsearch-7.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `18.84% <ø> (ø)` | | | [elasticsearch-8.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `19.04% <ø> (ø)` | | | [elasticsearch-8.x-v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.82% <ø> (+0.01%)` | :arrow_up: | | [grpc_v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `9.48% <ø> (ø)` | | | [grpc_v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `7.16% <ø> (ø)` | | | [kafka-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `9.74% <ø> (ø)` | | | [kafka-v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.82% <ø> (ø)` | | | [memory_v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.81% <ø> (ø)` | | | [opensearch-1.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `18.90% <ø> (+0.01%)` | :arrow_up: | | [opensearch-2.x-v1](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `18.89% <ø> (-0.02%)` | :arrow_down: | | [opensearch-2.x-v2](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `1.82% <ø> (+0.01%)` | :arrow_up: | | [tailsampling-processor](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `0.46% <ø> (ø)` | | | [unittests](https://app.codecov.io/gh/jaegertracing/jaeger/pull/5955/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing) | `95.30% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jaegertracing#carryforward-flags-in-the-pull-request-comment) to find out more.

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