Expand supports tokens tip, link to Token module

+1 to RTBC. The changes look good to me.

Steps followed for testing:

• Enable the module.
• Navigate to page /admin/structure/types/manage/{content-type} , look for Flippy settings
• Enable the option Build a pager for this content type
• Look for the description under the fields like Label for Previous, Next, first and last link.

Before MR:

After MR:

Thanks!