chore(docs): rename @private to @internal

The latter is understood by TypeScript's --stripInternal option, so this lets us
rely more on the tooling provided by typescript team.

docs/typescript-definition-package/processors/code_gen.js

@@ -49,7 +49,7 @@ DtsSerializer.prototype = {
   },
 
   member: function(buffer, ast) {
-    if (ast.private) return;
+    if (ast.private || ast.internal) return;
 
     buffer.push('\n');
     this.comment(buffer, ast.content);

docs/typescript-definition-package/processors/createTypeDefinitionFile.spec.js

@@ -25,22 +25,22 @@ describe('createTypeDefinitionFile processor', function() {
 
 
 
-  describe('classes with private constructors', function() {
-    
+  describe('classes with @internal constructors', function() {
+
     it('should convert heritage from `implements` into `extends`', function() {
-      
+
       // Create some mock docs for testing
       var docs = [
         {
           id: 'angular2/angular2',
           exports: [
-            { docType: 'class', heritage: 'implements Xyz', constructorDoc: { private: true }  }
+            { docType: 'class', heritage: 'implements Xyz', constructorDoc: { internal: true }  }
           ]
         }
       ];
 
       docs = processor.$process(docs);
-      
+
       expect(docs.length).toEqual(1);
       expect(docs[0].docType).toEqual('type-definition');
 
@@ -49,5 +49,5 @@ describe('createTypeDefinitionFile processor', function() {
       expect(moduleDoc.exports[0].heritage).toEqual('extends Xyz');
     });
   });
-	
+
 });