Add example of how to create a new trace in same process

examples/CreatingANewTraceInTheSameProcess.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+require __DIR__ . '/../vendor/autoload.php';
+
+use OpenTelemetry\SDK\Trace\SpanExporter\ConsoleSpanExporter;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+
+// Boilerplate setup to create a new tracer with console output
+$tracer = (new TracerProvider(
+    new SimpleSpanProcessor(
+        new ConsoleSpanExporter()
+    )
+))->getTracer();
+
+// This creates a span and sets it as the current parent (and root) span
+$rootSpan = $tracer->spanBuilder('foo')->startSpan();
+$rootScope = $rootSpan->activate();
+
+// This creates (and closes) a child span
+$childSpan = $tracer->spanBuilder('bar')->startSpan();
+$childSpan->end();
+
+// This closes the root/parent span and detaches its scope/context
+$rootSpan->end();
+$rootScope->detach();
+
+// This creates a new span as a parent/root, however regardless of calling "activate" on it, it will have a new TraceId
+$span = $tracer->spanBuilder('baz')->startSpan();
+$span->activate();
+
+$span->end();