fix(exporter-collector-grpc): incorrect URL format on docs after 0.20…

….0 update (#2266)

* fix(exporter-collector-grpc): incorrect default URL after 0.20.0 update

* fix collector metric exporter test assertion

* chore: add changes to README and revert other changes

packages/opentelemetry-exporter-collector-grpc/README.md

@@ -27,8 +27,8 @@ const { BasicTracerProvider, SimpleSpanProcessor } = require('@opentelemetry/tra
 const { CollectorTraceExporter } =  require('@opentelemetry/exporter-collector-grpc');
 
 const collectorOptions = {
-  // url is optional and can be omitted - default is localhost:4317
-  url: '<collector-hostname>:<port>',
+  // url is optional and can be omitted - default is grpc://localhost:4317
+  url: 'grpc://<collector-hostname>:<port>',
 };
 
 const provider = new BasicTracerProvider();
@@ -51,8 +51,8 @@ const { BasicTracerProvider, SimpleSpanProcessor } = require('@opentelemetry/tra
 const { CollectorTraceExporter } =  require('@opentelemetry/exporter-collector-grpc');
 
 const collectorOptions = {
-  // url is optional and can be omitted - default is localhost:4317
-  url: '<collector-hostname>:<port>',
+  // url is optional and can be omitted - default is grpc://localhost:4317
+  url: 'grpc://<collector-hostname>:<port>',
   credentials: grpc.credentials.createSsl(),
 };
 
@@ -91,8 +91,8 @@ const metadata = new grpc.Metadata();
 metadata.set('k', 'v');
 
 const collectorOptions = {
-  // url is optional and can be omitted - default is localhost:4317
-  url: '<collector-hostname>:<port>',
+  // url is optional and can be omitted - default is grpc://localhost:4317
+  url: 'grpc://<collector-hostname>:<port>',
   metadata, // // an optional grpc.Metadata object to be sent with each request
 };
 
@@ -116,8 +116,8 @@ The CollectorTraceExporter in Node expects the URL to only be the hostname. It w
 const { MeterProvider } = require('@opentelemetry/metrics');
 const { CollectorMetricExporter } =  require('@opentelemetry/exporter-collector-grpc');
 const collectorOptions = {
-  // url is optional and can be omitted - default is localhost:4317
-  url: '<collector-hostname>:<port>',
+  // url is optional and can be omitted - default is grpc://localhost:4317
+  url: 'grpc://<collector-hostname>:<port>',
 };
 const exporter = new CollectorMetricExporter(collectorOptions);