Update 1_16-default-policy-needs-to-be-updated.mdx (#27157)

Made a few grammar changes plus updating term from Vault IU to Vault UI

website/content/partials/known-issues/1_16-default-policy-needs-to-be-updated.mdx

@@ -25,12 +25,12 @@ path "sys/internal/ui/version" {
 ```
 
 However, the default policy for **existing** Vault servers does not update
-automatically during the upgrade. You must updated the policy manually in order
+automatically during the upgrade. You must update the policy manually in order
 for the Vault version to be displayed in the Vault UI.
 
-No other functionality in the Vault UI is affected be this issue.
+No other functionality in the Vault UI is affected by this issue.
 
-You can use the Vault CLI to update the **default** policy and allow the Vault IU to query the Vault server for version information:
+You can use the Vault CLI to update the **default** policy and allow the Vault UI to query the Vault server for version information:
 
 ```shell-session
 $ vault policy read default | cat - <<< '