doc: improve process.ppid 'added in' info

PR-URL: #29772
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: watson

doc/api/process.md

@@ -1637,7 +1637,10 @@ Android operating system. However, Android support in Node.js
 
 ## process.ppid
 <!-- YAML
-added: v9.2.0
+added:
+  - v9.2.0
+  - v8.10.0
+  - v6.13.0
 -->
 
 * {integer}