Update mdx/uk/README.md with correct date of status change

See ukf/ukf-meta#243 for details

mdx/uk/README.md

@@ -28,7 +28,7 @@ before being included in the `export` version consumed by interfederation partne
 
 ### Export Preview Aggregate vs. Export Aggregate
 
-Status (2021-02-02):
+Status (2021-02-23):
 
 * The `export-preview` aggregate declares the `alg` namespace on the document element,
   rather than on each `<DigestMethod>` or `<SigningMethod>` element.
@@ -60,7 +60,7 @@ when it appeared in the fallback aggregate, which would be too late to take corr
 
 ### Test Aggregate vs. Production Aggregate
 
-Status (2021-02-02):
+Status (2021-02-23):
 
 * The `test` aggregate does not include the `<UKFederationMember>` label (`ukf-meta#34`).
 
@@ -80,7 +80,7 @@ Status (2017-12-05):
 
 ### Fallback Aggregate vs. Production Aggregate
 
-Status (2021-02-02):
+Status (2021-02-23):
 
 * The `production` aggregate adds `<EncryptionMethod>` elements with AES128-CBC
   to SPs that have no block encryption methods listed