add node engine

Author: Sony Seng

README.md

@@ -3,6 +3,8 @@
 Node caching HTTP proxy built on top of [express-http-proxy](https://github.com/villadora/express-http-proxy). Persists requests and responses to an in-memory HAR-like data structure based on [HAR1.2](http://www.softwareishard.com/blog/har-12-spec/) . Caches JSON content-type responses by default with the ability to cache an entire site; including content-types describing images. Useful for testing front end code, mocking api, and saving the cache to a HAR file which can be used for further tests.
 ## Installation
 
+Requires Node >= 10
+
 Command line tool:
 ```
 $ npm install -g json-caching-proxy

package.json

@@ -1,12 +1,16 @@
 {
   "name": "json-caching-proxy",
-  "version": "1.5.0",
+  "version": "1.5.1",
   "description": "in-memory reverse caching HAR proxy",
   "keywords": [
     "cache",
     "proxy",
     "json"
   ],
+  "engines": {
+    "node": ">=10.0.0",
+    "npm": ">=6.0.0"
+  },
   "scripts": {
     "test": "mocha ./test/*.spec.js",
     "jsdoc": "jsdoc ./*.js -d ./jsdoc"