update readme doc

Author: SylvainJuge

span-stacktrace/README.md

@@ -6,51 +6,21 @@ This module provides a `SpanProcessor` that captures the [`code.stacktrace`](htt
 Capturing the stack trace is an expensive operation and does not provide any value on short-lived spans.
 As a consequence it should only be used when the span duration is known, thus on span end.
 
-However, the current SDK API does not allow to modify span attributes on span end, so we have to
-introduce other components to make it work as expected.
+## Usage and configuration
 
-## Usage
+This extension supports autoconfiguration.
 
-This extension does not support autoconfiguration because it needs to wrap the `SimpleSpanExporter`
-or `BatchingSpanProcessor` that invokes the `SpanExporter`.
+`otel.java.experimental.span-stacktrace.min.duration`:
+  - allows to configure the minimal duration for which spans have a stacktrace captured
+  - defaults to 5ms
+  - a value of zero will include all spans
+  - a negative value will disable the feature
 
-As a consequence you have to use [Manual SDK setup](#manual-sdk-setup)
-section below to configure it.
-
-### Manual SDK setup
-
-Here is an example registration of `StackTraceSpanProcessor` to capture stack trace for all
-the spans that have a duration >= 1 ms. The spans that have an `ignorespan` string attribute
-will be ignored.
-
-```java
-InMemorySpanExporter spansExporter = InMemorySpanExporter.create();
-SpanProcessor exportProcessor = SimpleSpanProcessor.create(spansExporter);
-
-Map<String, String> configMap = new HashMap<>();
-configMap.put("otel.java.experimental.span-stacktrace.min.duration", "1ms");
-ConfigProperties config = DefaultConfigProperties.createFromMap(configMap);
-
-Predicate<ReadableSpan> filterPredicate = readableSpan -> {
-  if(readableSpan.getAttribute(AttributeKey.stringKey("ignorespan")) != null){
-    return false;
-  }
-  return true;
-};
-SdkTracerProvider tracerProvider = SdkTracerProvider.builder()
-    .addSpanProcessor(new StackTraceSpanProcessor(exportProcessor, config, filterPredicate))
-    .build();
-
-OpenTelemetrySdk sdk = OpenTelemetrySdk.builder().setTracerProvider(tracerProvider).build();
-```
-
-### Configuration
-
-The `otel.java.experimental.span-stacktrace.min.duration` configuration option (defaults to 5ms) allows configuring
-the minimal duration for which spans should have a stacktrace captured.
-
-Setting `otel.java.experimental.span-stacktrace.min.duration` to zero will include all spans, and using a negative
-value will disable the feature.
+`otel.java.experimental.span-stacktrace.filter`:
+- allows to filter spans to be excluded from stacktrace capture
+- defaults to include all spans.
+- value is the class name of a class implementing `java.util.function.Predicate<ReadableSpan>`
+- filter class must be publicly accessible and provide a no-arg constructor
 
 ## Component owners