You can upload a file into an email to share documents, rather than adding as an email attachment - this is a neater and clearer way of linking to the files you need to share.
Step 1: Add a button
Firstly, you'll need to add a button to your email
Step 2: Link your file
Edit your button text and select File from the Link to drop down menu, then drag and drop or upload the file you'd like to add