Verify and update OTLP trace exporter documentation

exporters/otlp/otlptrace/README.md

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+# OpenTelemetry-Go OTLP Span Exporter
+
+OpenTelemetry Protocol (OTLP) Span Exporter.
+
+To constructs a new OTLP trace Exporter, you can follow this 
+ [`example`](https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/otlp/otlptrace/example_test.go).
+
+## Installation
+
+```
+go get -u go.opentelemetry.io/otel/exporters/otlp/otlptrace
+```
+
+## [`otlptrace`](https://pkg.go.dev/go.opentelemetry.io/otel/exporters/otlp/otlptrace)
+
+The `otlptrace` package provides an exporter implementing the OTel span exporter interface.
+This exporter is configured using a client satisfying the `otlptrace.Client` interface.
+This client handles the transformation of data into wire format and the transmission of that data to the collector.
+
+## [`otlptracegrpc`](https://pkg.go.dev/go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc)
+
+The `otlptracegrpc` package implements a gRPC client to be used in the span exporter.
+
+##  [`otlptracehttp`](https://pkg.go.dev/go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp)
+
+The `otlptracehttp` package implements a HTTP client to be used in the span exporter.

exporters/otlp/otlptrace/example_test.go

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+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otlptrace_test
+
+import (
+	"context"
+	"log"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+const (
+	instrumentationName    = "github.com/instrumentron"
+	instrumentationVersion = "v0.1.0"
+)
+
+var (
+	tracer = otel.GetTracerProvider().Tracer(
+		instrumentationName,
+		trace.WithInstrumentationVersion(instrumentationVersion),
+		trace.WithSchemaURL(semconv.SchemaURL),
+	)
+)
+
+func add(ctx context.Context, x, y int64) int64 {
+	var span trace.Span
+	_, span = tracer.Start(ctx, "Addition")
+	defer span.End()
+
+	return x + y
+}
+
+func multiply(ctx context.Context, x, y int64) int64 {
+	var span trace.Span
+	_, span = tracer.Start(ctx, "Multiplication")
+	defer span.End()
+
+	return x * y
+}
+
+func Resource() *resource.Resource {
+	return resource.NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.ServiceNameKey.String("otlptrace-example"),
+		semconv.ServiceVersionKey.String("0.0.1"),
+	)
+}
+
+func InstallExportPipeline(ctx context.Context) func() {
+	client := otlptracehttp.NewClient()
+	exporter, err := otlptrace.New(ctx, client)
+	if err != nil {
+		log.Fatalf("creating OTLP trace exporter: %v", err)
+	}
+
+	tracerProvider := sdktrace.NewTracerProvider(
+		sdktrace.WithBatcher(exporter),
+		sdktrace.WithResource(Resource()),
+	)
+	otel.SetTracerProvider(tracerProvider)
+
+	return func() {
+		if err := tracerProvider.Shutdown(ctx); err != nil {
+			log.Fatalf("stopping tracer provider: %v", err)
+		}
+	}
+}
+
+func Example() {
+	ctx := context.Background()
+	// Registers a tracer Provider globally.
+	cleanup := InstallExportPipeline(ctx)
+	defer cleanup()
+
+	log.Println("the answer is", add(ctx, multiply(ctx, multiply(ctx, 2, 2), 10), 2))
+}