chore(dgeni): fixing npm install instructions

scripts/docs/processors/npm-id.js

@@ -0,0 +1,24 @@
+module.exports = function npmId(renderDocsProcessor) {
+  return {
+    name: 'npm-id',
+    $runAfter: ['paths-computed'],
+    $runBefore: ['rendering-docs'],
+    $process: function(docs) {
+      var currentVersion = renderDocsProcessor.extraData.version.current.name;
+
+      // pretty up and sort the docs object for menu generation
+      docs = docs.filter(function(doc) {
+        return (!!doc.name && !!doc.outputPath) || doc.docType === 'index-page';
+      });
+
+      docs.forEach(function(doc, i) {
+        doc.npmId = doc.outputPath.replace('/README.md', '')
+          .replace('src/@ionic-native/plugins/','')
+          .replace('@ionic-native/plugins/','');
+      });
+
+      // returning docs will replace docs object in the next process
+      return docs;
+    }
+  };
+};