[chore][processor/tailsampling] Better description for rate_limiting (#…

…36721)

Fixes #35419

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>
Co-authored-by: Curtis Robert <crobert@splunk.com>

processor/tailsamplingprocessor/README.md

@@ -31,7 +31,7 @@ Multiple policies exist today and it is straight forward to add more. These incl
 - `status_code`: Sample based upon the status code (`OK`, `ERROR` or `UNSET`)
 - `string_attribute`: Sample based on string attributes (resource and record) value matches, both exact and regex value matches are supported
 - `trace_state`: Sample based on [TraceState](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/api.md#tracestate) value matches
-- `rate_limiting`: Sample based on rate
+- `rate_limiting`: Sample based on the rate of spans per second.
 - `span_count`: Sample based on the minimum and/or maximum number of spans, inclusive. If the sum of all spans in the trace is outside the range threshold, the trace will not be sampled.
 - `boolean_attribute`: Sample based on boolean attribute (resource and record).
 - `ottl_condition`: Sample based on given boolean OTTL condition (span and span event).