chore: fix usage instructions from READMEs (#836)

packages/opentelemetry-node/README.md

@@ -39,12 +39,11 @@ Additionally to automated instrumentation, `NodeTracerProvider` exposes the same
 ## Installation
 
 ```bash
-npm install --save @opentelemetry/core
+npm install --save @opentelemetry/api
 npm install --save @opentelemetry/node
 
 # Install instrumentation plugins
 npm install --save @opentelemetry/plugin-http
-npm install --save @opentelemetry/plugin-grpc
 npm install --save @opentelemetry/plugin-https
 ```
 
@@ -53,7 +52,7 @@ npm install --save @opentelemetry/plugin-https
 The following code will configure the `NodeTracerProvider` to instrument `http` using `@opentelemetry/plugin-http`.
 
 ```js
-const opentelemetry = require('@opentelemetry/core');
+const opentelemetry = require('@opentelemetry/api');
 const { NodeTracerProvider } = require('@opentelemetry/node');
 
 // Create and configure NodeTracerProvider
@@ -79,7 +78,7 @@ const http = require('http');
 To enable instrumentation for all [supported modules](https://github.com/open-telemetry/opentelemetry-js#plugins), create an instance of `NodeTracerProvider` without providing any plugin configuration to the constructor.
 
 ```js
-const opentelemetry = require('@opentelemetry/core');
+const opentelemetry = require('@opentelemetry/api');
 const { NodeTracerProvider } = require('@opentelemetry/node');
 
 // Create and initialize NodeTracerProvider

packages/opentelemetry-plugin-dns/README.md

@@ -36,7 +36,7 @@ const provider = new NodeTracerProvider({
 
 If you use Zipkin, you must use `ignoreHostnames` in order to not trace those calls. If the server is local. You can set :
 
-```
+```js
 const provider = new NodeTracerProvider({
   plugins: {
     dns: {

packages/opentelemetry-plugin-document-load/README.md

@@ -17,16 +17,16 @@ npm install --save @opentelemetry/plugin-document-load
 
 ```js
 import { ConsoleSpanExporter, SimpleSpanProcessor } from '@opentelemetry/tracing';
-import { WebTracer } from '@opentelemetry/web';
+import { WebTracerProvider } from '@opentelemetry/web';
 import { DocumentLoad } from '@opentelemetry/plugin-document-load';
 
-const webTracer = new WebTracer({
+const provider = new WebTracerProvider({
   plugins: [
     new DocumentLoad()
   ]
 });
 
-webTracer.addSpanProcessor(new SimpleSpanProcessor(new ConsoleSpanExporter()));
+provider.addSpanProcessor(new SimpleSpanProcessor(new ConsoleSpanExporter()));
 ```
 
 ## Optional: Send a trace parent from your server

packages/opentelemetry-plugin-user-interaction/README.md

@@ -21,19 +21,19 @@ npm install --save @opentelemetry/plugin-user-interaction
 
 ```js
 import { ConsoleSpanExporter, SimpleSpanProcessor } from '@opentelemetry/tracing';
-import { WebTracer } from '@opentelemetry/web';
+import { WebTracerProvider } from '@opentelemetry/web';
 import { UserInteractionPlugin } from '@opentelemetry/plugin-user-interaction';
 import { ZoneScopeManager } from '@opentelemetry/scope-zone';
 // or if you already have zone.js
 // import { ZoneScopeManager } from '@opentelemetry/scope-zone-peer-dep';
 
-const webTracerWithZone = new WebTracer({
+const provider = new WebTracerProvider({
   scopeManager: new ZoneScopeManager(), // optional
   plugins: [
     new UserInteractionPlugin()
   ]
 });
-webTracerWithZone.addSpanProcessor(new SimpleSpanProcessor(new ConsoleSpanExporter()));
+provider.addSpanProcessor(new SimpleSpanProcessor(new ConsoleSpanExporter()));
 
 // and some test
 const btn1 = document.createElement('button');

packages/opentelemetry-tracing/README.md

@@ -17,7 +17,7 @@ For automated instrumentation for Node.js, please see
 ## Installation
 
 ```bash
-npm install --save @opentelemetry/core
+npm install --save @opentelemetry/api
 npm install --save @opentelemetry/tracing
 ```