Rename eslint config to 'eslint-config-react-native-community' (#23718)

Summary:
Renamed `eslint-config-react-native` to `eslint-config-react-native-community`, due to the fact, that initial name is already taken on `npm`. Additionally, I added very simple `README.md` file, to prepare the package to be published.

[General] [Changed] - Changed `eslint-config-react-native` name to `eslint-config-react-native-community`
Pull Request resolved: https://github.com/facebook/react-native/pull/23718

Differential Revision: D14298553

Pulled By: cpojer

fbshipit-source-id: bad5a42502ccdebf5f95d8217187be23bbf8f26c

.eslintrc

@@ -2,7 +2,7 @@
   "root": true,
 
   "extends": [
-    "./packages/eslint-config-react-native/index.js"
+    "./packages/eslint-config-react-native-community/index.js"
   ],
 
   "overrides": [

packages/eslint-config-react-native-community/README.md

@@ -0,0 +1,19 @@
+# eslint-config-react-native-community
+
+## Installation
+
+```
+yarn add --dev eslint @react-native-community/eslint-config
+```
+
+*Note: We're using `yarn` to install deps. Feel free to change commands to use `npm` 3+ and `npx` if you like*
+
+## Usage
+
+Add to your eslint config (`.eslintrc`, or `eslintConfig` field in `package.json`):
+
+```json
+{
+    "extends": "@react-native-community"
+}
+```

packages/eslint-config-react-native-community/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "eslint-config-react-native",
+  "name": "@react-native-community/eslint-config",
   "version": "0.0.0",
   "description": "ESLint config for React Native",
   "main": "index.js",