docs: fix pagination example

Author: ricellis

README.md

@@ -1217,7 +1217,7 @@ to continue paging.
 # Option: use pager next page
 # For retrieving one page at a time with a method call.
 pager: Pager = pagination.pager()
-if pager.get_next():
+if pager.has_next():
     page = pager.get_next()
     # Do something with page
 ```