chore(schemas): refine version_removed description

Author: caugner

schemas/compat-data-schema.md

@@ -305,7 +305,7 @@ This is the only mandatory property and it is `false` or contains a string with
 
 #### `version_removed`
 
-Contains a string with the version number the subfeature was removed in. If the feature has not been removed from the browser, this property is omitted, rather than being set to `false`.
+This optional property contains a string with the version number when the subfeature ceased to be supported. If the feature has not been removed from the browser, this property is omitted.
 
 Examples:
 

schemas/public.schema.md

@@ -193,7 +193,7 @@ This is the only mandatory property and it is `false` or contains a string with
 
 #### `version_removed`
 
-Contains a string with the version number the subfeature was removed in. If the feature has not been removed from the browser, this property is omitted. When `version_removed` is present, `version_last` is always present as well.
+This optional property contains a string with the version number when the subfeature ceased to be supported. If the feature has not been removed from the browser, this property is omitted.
 
 Example: