Update documentation of v2 endpoints for RUM retention filters.

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See DataDog/datadog-api-spec#3634 Test branch datadog-api-spec/test/kwangjun.kim/RUM-8778/2/update-documentation

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Datadog Report

Branch report: datadog-api-spec/generated/3634 Commit report: 1637e0b Test service: datadog-api-client-ruby

:white_check_mark: 0 Failed, 1031 Passed, 2068 Skipped, 1m 51.15s Total duration (1m 30.24s time saved)

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