[mod] simple theme - add ESLint

[1] https://eslint.org/
[2] https://eslint.org/docs/user-guide/configuring/
[3] https://eslint.org/docs/user-guide/command-line-interface

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/static/themes/simple/.eslintrc.json

@@ -0,0 +1,13 @@
+{
+    "env": {
+        "browser": true,
+        "es2021": true
+    },
+    "extends": "eslint:recommended",
+    "parserOptions": {
+        "ecmaVersion": 12,
+        "sourceType": "module"
+    },
+    "rules": {
+    }
+}