Fix/enum-keyword (#291)

Author: jeremyfiel

content/2019-09/validation/enum.markdown

@@ -1,7 +1,7 @@
 ---
 keyword: "enum"
 signature: "Array<Any>"
-value: This keyword must be set to a *non-empty* array of unique JSON values
+value: This keyword must be set to an array of unique JSON values
 summary: "Validation succeeds if the instance is equal to one of the elements in this keyword's array value."
 kind: [ "assertion" ]
 instance: [ "any" ]

content/2020-12/validation/enum.markdown

@@ -1,7 +1,7 @@
 ---
 keyword: "enum"
 signature: "Array<Any>"
-value: This keyword must be set to a *non-empty* array of unique JSON values
+value: This keyword must be set to an array of unique JSON values
 summary: "Validation succeeds if the instance is equal to one of the elements in this keyword's array value."
 kind: [ "assertion" ]
 instance: [ "any" ]
@@ -11,6 +11,8 @@ tests:
   - draft2020-12/enum.json
 index: -99998
 introduced_in: draft1
+changed_in:
+  - 2019-09
 related:
   - vocabulary: validation
     keyword: const