rename app config to internal config

Author: koddsson

docs/configs.md

@@ -22,7 +22,6 @@ $ node_modules/.bin/eslint-github-init
 
 A base layer of configuration recommended for any JS project. The [Prettier](https://prettier.io/) formatter is used to format code.
 
+### `plugin:github/internal`
 
-### `plugin:github/app`
-
-Recommended rules when writing a browser application.
+Recommended rules when writing a internal GitHub app.

lib/configs/app.js renamed to lib/configs/internal.js

@@ -15,7 +15,7 @@ module.exports = {
     'unescaped-html-literal': require('./rules/unescaped-html-literal')
   },
   configs: {
-    app: require('./configs/app'),
+    internal: require('./configs/internal'),
     browser: require('./configs/browser'),
     recommended: require('./configs/recommended'),
     typescript: require('./configs/typescript')