"Add Book" in lieu of "Create Book" in book-detail.component.html?

[abergquist]

While working on the first exercise, it occurred to me that -- although I know we're creating a record under the covers -- it might be a little more user-friendly to display "Add Book" in lieu of "Create Book" in the following line of book-detail.component.html:

<ng-template #prompt>Create Book</ng-template>

(Not sure if this would necessitate replacing other occurrences of "Create"/"create" with "Add"/"add" throughout the code.)