Update CHANGELOG for #607

Author: duckontheweb

CHANGELOG.md

@@ -13,6 +13,7 @@
 - Enable [strict
   mode](https://mypy.readthedocs.io/en/latest/command_line.html?highlight=strict%20mode#cmdoption-mypy-strict)
   for `mypy` ([#591](https://github.com/stac-utils/pystac/pull/591))
+- Links will get their `title` from their target if no `title` is provided ([#607](https://github.com/stac-utils/pystac/pull/607))
 
 ### Fixed