Fix tiny issue of doc in RandomRatioBased

Author: alvinlin123

pkg/tracing/sampler/sampling.go

@@ -17,7 +17,7 @@ type RandomRatioBased struct {
 	fraction float64
 }
 
-// NewRandomRatioBased crea
+// NewRandomRatioBased creates a sampler based on random number.
 // fraction parameter should be between 0 and 1 where:
 // fraction >= 1 it will always sample
 // fraction <= 0 it will never sample
@@ -31,6 +31,7 @@ func NewRandomRatioBased(fraction float64, rnd randGenerator) sdktrace.Sampler {
 	return &RandomRatioBased{rnd: rnd, fraction: fraction}
 }
 
+// ShouldSample impleents sdktrace.Sampler.ShouldSample.
 func (s *RandomRatioBased) ShouldSample(p sdktrace.SamplingParameters) sdktrace.SamplingResult {
 	psc := trace.SpanContextFromContext(p.ParentContext)
 	shouldSample := s.rnd.Float64() < s.fraction
@@ -46,6 +47,7 @@ func (s *RandomRatioBased) ShouldSample(p sdktrace.SamplingParameters) sdktrace.
 	}
 }
 
+// Description implements sdktrace.Sampler.Description.
 func (s *RandomRatioBased) Description() string {
 	return fmt.Sprintf("RandomRatioBased{%g}", s.fraction)
 }