Fix typos / improve syntax

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/ChangeLog.d/driver-only-cipher.txt b/ChangeLog.d/driver-only-cipher.txt
index e2a946c..331b2f9 100644
--- a/ChangeLog.d/driver-only-cipher.txt
+++ b/ChangeLog.d/driver-only-cipher.txt
@@ -2,7 +2,7 @@
    * If a cipher or AEAD mechanism has a PSA driver, you can now build the
      library without the corresponding built-in implementation. Generally
      speaking that requires both the key type and algorithm to be accelerated
-     or they'll both be built in. However for CCM and GCM the built-in
+     or they'll both be built in. However, for CCM and GCM the built-in
      implementation is able to take advantage of a driver that only
      accelerates the key type (that is, the block cipher primitive). See
      docs/driver-only-builds.md for full details and current limitations.