Warn on intitialization of Simple SpanProcessor (#3854)

* add warning log about using simpleSpanProcessor in production

* add changelog entry

* fix changelog

* switch to using the new Warn logging function

* revert alignment formatting in changelog

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -22,6 +22,7 @@ See our [versioning policy](VERSIONING.md) for more information about these stab
   Both the `DataPoint` and `HistogramDataPoint` types from that package have a new field of `Exemplars` containing the sampled exemplars for their timeseries. (#3849)
 - Configuration for each metric instrument in `go.opentelemetry.io/otel/sdk/metric/instrument`. (#3895)
 - The internal logging introduces a warning level verbosity equal to `V(1)`. (#3900)
+- Added a log message warning about usage of `SimpleSpanProcessor` in production environments. (#3854)
 
 ### Changed
 

sdk/trace/simple_span_processor.go

@@ -19,6 +19,7 @@ import (
 	"sync"
 
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/internal/global"
 )
 
 // simpleSpanProcessor is a SpanProcessor that synchronously sends all
@@ -43,6 +44,8 @@ func NewSimpleSpanProcessor(exporter SpanExporter) SpanProcessor {
 	ssp := &simpleSpanProcessor{
 		exporter: exporter,
 	}
+	global.Warn("SimpleSpanProcessor is not recommended for production use, consider using BatchSpanProcessor instead.")
+
 	return ssp
 }