chore: update changelog

Author: Erin van der Veen

CHANGELOG.md

@@ -46,6 +46,7 @@ This name should be decided amongst the team before the release.
 
 ### Added
 - [#705](https://github.com/tweag/topiary/pull/705) Added support for Nickel 1.7 extended pattern formatting
+- [#737](https://github.com/tweag/topiary/pull/737) Added the `prefetch` command, that prefetches and caches all grammars in the current configuration
 
 ### Fixed
 - [#720](https://github.com/tweag/topiary/pull/720) [#722](https://github.com/tweag/topiary/pull/722) [#723](https://github.com/tweag/topiary/pull/723) [#724](https://github.com/tweag/topiary/pull/724) [#735](https://github.com/tweag/topiary/pull/735)