Specify supported Node versions (#196)

Author: Ndpnt

content/collections/tutorial/create.md

@@ -14,7 +14,7 @@ By the end, you'll have a working collection that tracks changes to a service's
 
 ## Prerequisites
 
-- [Node.js](https://nodejs.org/en) is installed on your system.
+- [Node.js](https://nodejs.org/en) (version {{< engine-package key="engines.node" >}}) is installed on your system.
 - You have basic familiarity with the command line.
 - You know how to use a text editor.
 

content/terms/how-to/track-terms.md

@@ -16,7 +16,7 @@ Having understood briefly how a declaration is structured in JSON format, we nee
 
 In order to add declarations:
 
-1. You need to have [Node.js](https://nodejs.org/en/) installed on your machine. If you don't have it, you can download it from the official website [here](https://nodejs.org/en/download/).
+1. You need to have [Node.js](https://nodejs.org/en/) (version {{< engine-package key="engines.node" >}}) installed on your machine. If you don't have it, you can download it from the official website [here](https://nodejs.org/en/download/).
 2. You need to have git installed on your machine. If you don't have it, you can download it from the official website [here](https://git-scm.com/downloads).
 
 ## Adding a declaration

content/terms/tutorial/track.md

@@ -12,7 +12,7 @@ By the end, you'll have tracked a service's privacy policy. You will also have a
 
 ## Prerequisites
 
-- [Node.js](https://nodejs.org/en) is installed on your system.
+- [Node.js](https://nodejs.org/en) (version {{< engine-package key="engines.node" >}}) is installed on your system.
 - You have basic familiarity with the command line.
 - You have basic familiarity with HTML and CSS selectors.
 - You know how to use a text editor.

layouts/shortcodes/engine-package.html

@@ -0,0 +1,13 @@
+{{ $enginePackage := readFile "node_modules/@opentermsarchive/engine/package.json" | unmarshal }}
+{{ $key := .Get "key" }}
+
+{{ $value := $enginePackage }}
+{{ range split $key "." }}
+  {{ $value = index $value . }}
+{{ end }}
+
+{{- if $value -}}
+  {{- $value -}}
+{{- else -}}
+  {{- warnf "Key '%s' not found in engine package.json" $key -}}
+{{- end -}}