Prefer .jsx for JSX files

Author: jakezatecky

.editorconfig

@@ -13,5 +13,5 @@ insert_final_newline = true
 [*.md]
 trim_trailing_whitespace = false
 
-[*.js]
+[*.{js,jsx}]
 indent_size = 4

.eslintrc

@@ -3,6 +3,11 @@
   "env": {
     "node": true
   },
+  "rules": {
+    "react/jsx-filename-extension": ["error", {
+      "allow": "as-needed"
+    }]
+  },
   "settings": {
     "import/resolver": {
       "webpack": {