Update CHANGELOG.md

Author: Paddy

CHANGELOG.md

@@ -11,6 +11,7 @@ BUG FIXES
 * Check for `nil` errors prior to invoking `ErrorCheck` [GH-646]
 * More reliable handling of logging [GH-639]
 * Modified error text to make golint and go vet happy when a non-empty plan is found in testing and an empty plan was expected [GH-596]
+* Add `UseJSONNumber` to `helper/schema.Resource` to make it possible to represent large numbers precisely. Setting to `true` will make numbers appear as `json.Number` in `StateUpgrader`s instead of as `float64`. [GH-662]
 
 NOTES