message: docs: rename as server middleware title
diff: @@ -83,7 +83,7 @@ import 'graphql-playground/playground.css'
  ReactDOM.render(<Playground endpoint="https://api.graph.cool/simple/v1/swapi" />, document.body)
  ```
  -### As a server Middleware
  +### As Server Middleware
  #### Install
  ```sh
  @@ -104,9 +104,9 @@ We have a full example for each of the frameworks below:
  - **Koa:** See [packages/graphql-playground-middleware/examples/koa](https://github.com/graphcool/graphql-playground/tree/master/packages/graphql-playground-middleware/examples/koa)
  -- **Lambda (as a serverless handler):** See [serverless-graphql-apollo](https://github.com/serverless/serverless-graphql-apollo) or a quick example below.
  +- **Lambda (as serverless handler):** See [serverless-graphql-apollo](https://github.com/serverless/serverless-graphql-apollo) or a quick example below.
  -### As a serverless handler
  +### As serverless handler
  #### Install
  ```sh
  yarn add graphql-playground-middleware-lambda
  