Deprecate support for now.json and package.json (#489)

* Removed now.json from readme

* Emit warning message if using now.json or package.json

Author: leo

README.md

@@ -36,7 +36,7 @@ Now you understand how the package works! :tada:
 
 ## Configuration
 
-To customize `serve`'s behavior, create a `serve.json` file and insert any of [these properties](https://github.com/zeit/serve-handler#options). In addition, `serve` will also detect `now.json` files if they contain the `static` property.
+To customize `serve`'s behavior, create a `serve.json` file and insert any of [these properties](https://github.com/zeit/serve-handler#options).
 
 ## API
 

bin/serve.js

@@ -284,6 +284,10 @@ const loadConfig = async (cwd, entry, args) => {
 		Object.assign(config, content);
 		console.log(info(`Discovered configuration in \`${file}\``));
 
+		if (file === 'now.json' || file === 'package.json') {
+			console.error(warning('The config files `now.json` and `package.json` are deprecated. Please use `serve.json`.'));
+		}
+
 		break;
 	}