Update CHANGELOG for #590

Author: duckontheweb

CHANGELOG.md

@@ -4,10 +4,17 @@
 
 ### Added
 
+- "Public" `Catalog.stac_io` property to match "private" `Catalog._stac_io` attribute
+  ([#590](https://github.com/stac-utils/pystac/pull/590))
+
 ### Removed
 
 ### Changed
 
+- `Catalog.set_root` also sets `Catalog.stac_io` for the calling instance to be the same
+  as `root.stac_io`, if that value is not `None`
+  ([#590](https://github.com/stac-utils/pystac/pull/590))
+
 ### Fixed
 
 ### Deprecated