[processor/groupbytrace] Add num_workers doc to README

processor/groupbytraceprocessor/README.md

@@ -28,15 +28,19 @@ processors:
  groupbytrace/2:
  wait_duration: 10s
  num_traces: 1000
+ num_workers: 2
 ```
 
 ## Configuration
 
 Refer to [config.yaml](./testdata/config.yaml) for detailed examples on using the processor.
 
-The `num_traces` property tells the processor what's the maximum number of traces to keep in the internal storage. A higher `num_traces` might incur in a higher memory usage.
+The `num_traces` (default=1,000,000) property tells the processor what's the maximum number of traces to keep in the internal storage. A higher `num_traces` might incur in a higher memory usage.
 
-The `wait_duration` property tells the processor for how long it should keep traces in the internal storage. Once a trace is kept for this duration, it's then released to the next consumer and removed from the internal storage. Spans from a trace that has been released will be kept for the entire duration again.
+The `wait_duration` (default=1s) property tells the processor for how long it should keep traces in the internal storage. Once a trace is kept for this duration, it's then released to the next consumer and removed from the internal storage. Spans from a trace that has been released will be kept for the entire duration again.
+
+The `num_workers` (default=1) property controls how many concurrent workers the processor will use to process traces. If you are looking to optimize this value
+then using GOMAXPROCS could be considered as a starting point. 
 
 ## Metrics
 

processor/groupbytraceprocessor/config.go

@@ -25,7 +25,7 @@ type Config struct {
  // Default: 1_000_000.
  NumTraces int `mapstructure:"num_traces"`
 
- // NumWorkers is a number of workers processing event queue. Should be equal to physical processors number.
+ // NumWorkers is a number of workers processing event queue.
  // Default: 1.
  NumWorkers int `mapstructure:"num_workers"`