Not only can you make annotations on your documents, but you can also bookmark certain pages if needed. To bookmark a page:
Scroll to the page in the document you want to bookmark
Click the dropdown menu in the upper left corner, next to the page counter, and click "Bookmarks"
Click "New Bookmark" and enter the name you want to call it.
When you click on the bookmark, you will automatically jump to that page in your document. If you need to change the name or delete it, just click the pencil icon next to the bookmark.