message: fixes in Ttypescript example
diff: @@ -231,6 +231,7 @@ type ConditionValue = string | number | boolean | Date | null;
  ```
  class Product {
  constructor(
  + id = null,
  title = '',
  price = 0,
  currency = 'USD',
  @@ -250,7 +251,7 @@ class Product {
  2. For store model just pass it's instance without speciying colleciton prefix (e.g. `Products/`). Collection name will be detected automatically by model's class name
  ```
  let product = new Product(
  - 'iPhone X', 999.99, 'USD', 64, 'Apple', true,
  + null, 'iPhone X', 999.99, 'USD', 64, 'Apple', true,
  new Date('2017-10-01T00:00:00')
  };
  @@ -305,6 +306,7 @@ All datatype definitions you can find in `lib/ravendb-node.d.ts`. An example of
  // models/Product.ts
  export class Product {
  constructor(
  + public id: string = null,
  public title: string = '',
  public price: number = 0,
  public currency: string = 'USD',
  @@ -330,7 +332,7 @@ store.conventions.addDocumentInfoResolver({
  (async (): Promise<void> => {
  let product: Product = new Product(
  - 'iPhone X', 999.99, 'USD', 64, 'Apple', true,
  + null, 'iPhone X', 999.99, 'USD', 64, 'Apple', true,
  new Date('2017-10-01T00:00:00')
  };
  