chore: update HTTP Readme (#343)

README.md

@@ -41,6 +41,8 @@ OpenTelemetry can collect tracing data automatically using plugins. Vendors/User
 - [@opentelemetry/plugin-http](https://github.com/open-telemetry/opentelemetry-js/tree/master/packages/opentelemetry-plugin-http)
 - [@opentelemetry/plugin-grpc](https://github.com/open-telemetry/opentelemetry-js/tree/master/packages/opentelemetry-plugin-grpc)
 
+To request automatic tracing support for a module not on this list, please [file an issue](https://github.com/open-telemetry/opentelemetry-js/issues). Alternatively, you can write a plugin yourself.
+
 ### Shims
 
 | Package                 | Description |

examples/http/README.md

@@ -2,6 +2,15 @@
 
 OpenTelemetry HTTP Instrumentation allows the user to automatically collect trace data and export them to the backend of choice (we can use Zipkin or Jaeger for this example), to give observability to distributed systems.
 
+This is a simple example that demonstrates tracing HTTP request from client to server. The example
+shows key aspects of tracing such as
+- Root Span (on Client)
+- Child Span (on Client)
+- Child Span from a Remote Parent (on Server)
+- SpanContext Propagation (from Client to Server)
+- Span Events
+- Span Attributes
+
 ## Installation
 
 ```sh
@@ -65,4 +74,4 @@ Go to Jaeger with your browser [http://localhost:16686/trace/(your-trace-id)]()
 
 ## LICENSE
 
-Apache License 2.0
+Apache License 2.0

packages/opentelemetry-plugin-http/README.md

@@ -17,11 +17,32 @@ npm install --save @opentelemetry/plugin-http
 
 ## Usage
 
+OpenTelemetry HTTP Instrumentation allows the user to automatically collect trace data and export them to the backend of choice, to give observability to distributed systems.
+
+To load a specific plugin (HTTP in this case), specify it in the Node Tracer's configuration.
+```
+const { NodeTracer } = require('@opentelemetry/node-sdk');
+
+const tracer = new NodeTracer({
+  plugins: {
+    http: {
+      enabled: true,
+      // You may use a package name or absolute path to the file.
+      path: '@opentelemetry/plugin-http',
+      ignoreOutgoingUrls: [/spans/]
+    }
+  }
+});
 ```
-const opentelemetry = require('@opentelemetry/plugin-http');
 
-// TODO: DEMONSTRATE API
+To load all the [supported plugins](https://github.com/open-telemetry/opentelemetry-js#plugins), use below approach. Each plugin is only loaded when the module that it patches is loaded; in other words, there is no computational overhead for listing plugins for unused modules.
 ```
+const { NodeTracer } = require('@opentelemetry/node-sdk');
+
+const tracer = new NodeTracer();
+```
+
+See [examples/http](https://github.com/open-telemetry/opentelemetry-js/tree/master/examples/http) for a short example.
 
 ## Useful links
 - For more information on OpenTelemetry, visit: <https://opentelemetry.io/>