fix: add strict engines restriction when installing generator and upd…

…ate readme (#286)

* docs: update readme with information about requirements
* fix: add strict engines restriction when installing the generator

.npmrc

@@ -0,0 +1 @@
+engine-strict=true

README.md

@@ -9,6 +9,13 @@
 
 > :warning: This package doesn't support AsyncAPI 1.x anymore. We recommend to upgrade to the latest AsyncAPI version using the [AsyncAPI converter](https://github.com/asyncapi/converter). If you need to convert documents on the fly, you may use the [Node.js](https://github.com/asyncapi/converter) or [Go](https://github.com/asyncapi/converter-go) converters.
 
+## Requirements
+
+* Node.js v12.16+
+* npm v6.13.7+
+
+Install both packages using [official installer](https://nodejs.org/en/download/). After installation make sure both packages have proper version by running `node -v` and `npm -v`. To upgrade invalid npm version run `npm install npm@latest -g`
+
 ## Install
 
 ```bash
@@ -106,10 +113,6 @@ See [API documentation](docs/api.md).
 
 See [authoring templates](docs/authoring.md) and the [list of templates recipes](docs/templates-recipes.md).
 
-## Requirements
-
-* Node.js v12.16+
-
 ## Contributing
 
 Read [CONTRIBUTING](CONTRIBUTING.md) guide.

package.json

@@ -7,6 +7,10 @@
     "asyncapi-generator": "./cli.js",
     "ag": "./cli.js"
   },
+  "engines": {
+    "node": ">=12.16",
+    "npm": ">=6.13.7"
+  },
   "scripts": {
     "docs": "jsdoc2md lib/generator.js > docs/api.md",
     "release": "semantic-release",