Update changelog

Author: zimurgh

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to release number versioning.
 - Added Docker containers with docker-compose [#10](https://github.com/CodeForPhilly/third-places/pull/10)
 - Set up Leaflet React component and boiletplate homepage[#7](https://github.com/CodeForPhilly/third-places/issues/7)
 - Added initial Django models & migration [#21](https://github.com/CodeForPhilly/third-places/pull/21)
+- Added initial REST endpoints for Users [#23](https://github.com/CodeForPhilly/third-places/pull/23)
 - Added buttons at bottom of Map [#40](https://github.com/CodeForPhilly/third-places/pull/40)
 
 ### Changed