Fix date formatting in release notes

Bug: 154128320
Test: ./generateReleaseNotes.py 1586970000000
Test: ./testReleasenotes.py
Change-Id: If17f2f0351d63dd66f0f4139159ce5a8ff8368cb
diff --git a/development/release-notes/AndroidXMarkdown.py b/development/release-notes/AndroidXMarkdown.py
index c5ca7f8..6441156 100644
--- a/development/release-notes/AndroidXMarkdown.py
+++ b/development/release-notes/AndroidXMarkdown.py
@@ -132,7 +132,7 @@
 		self.groupId = groupId
 		self.artifactIds = artifactIds
 		self.version = version
-		self.releaseDate = releaseDate
+		self.releaseDate = MarkdownDate(releaseDate)
 		self.fromSHA = fromSHA
 		self.untilSHA = untilSHA
 		self.projectDir = projectDir