Google has recently updated the blogger interface and has introduced so many great features. One of the features of the blogger is that you can put a jump break in the article and if you are showing multiple blogs on the landing page, then that break will put a jump and a Read more link.
With new changes, the option has moved. To insert jump break in the page you have to be in the Compose View and in the toolbar click ... and then choose Insert Jump break as shown in the image below.