I've received an email titled "Documents have been updated" informing me that some changes were introduced in some our documents (no surprise here of course). But I'd like to know if there is any difference between the sentence:
Documents have been updated.
and the sentences
Documents are updated.
Documents were updated.
They seem to mean the same thing (or very similar). Could there be any reason to use the present perfect in this email's title (instead of "Documents are updated" or Documents were updated)?