package-json: add pnpm

exposures/configs/package-json.yaml

@@ -4,10 +4,11 @@ info:
   name: npm package.json disclosure
   author: geeknik,afaq,noraj
   severity: info
-  description: All NodeJS packages contain a file, usually in the project root, called package.json - this file holds various metadata relevant to the project generated by package managers such as npm or yarn.
+  description: All NodeJS packages contain a file, usually in the project root, called package.json - this file holds various metadata relevant to the project generated by package managers such as npm, yarn, pnpm.
   reference:
     - https://docs.npmjs.com/cli/v9/configuring-npm/package-json
     - https://classic.yarnpkg.com/lang/en/docs/package-json/
+    - https://pnpm.io/package_json
   tags: config,exposure
 
 requests: