Generalize MAC zeroization changelog entry

Signed-off-by: Gilles Peskine <[email protected]>

ChangeLog.d/mac-zeroize.txt

@@ -0,0 +1,6 @@
+Security
+   * Zeroize several intermediate variables used to calculate the expected
+     value when verifying a MAC or AEAD tag. This hardens the library in
+     case the value leaks through a memory disclosure vulnerability. For
+     example, a memory disclosure vulnerability could have allowed a
+     man-in-the-middle to inject fake ciphertext into a DTLS connection.

ChangeLog.d/ssl-mac-zeroize.txt

@@ -1,5 +0,0 @@
-Security
-   * Zeroize intermediate variables used to calculate the MAC in CBC cipher
-     suites. This hardens the library in case stack memory leaks through a
-     memory disclosure vulnerabilty, which could formerly have allowed a
-     man-in-the-middle to inject fake ciphertext into a DTLS connection.