Add a ChangeLog entry for driver-only hashes

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/ChangeLog.d/driver-only-hashes.txt b/ChangeLog.d/driver-only-hashes.txt
new file mode 100644
index 0000000..4967bb1
--- /dev/null
+++ b/ChangeLog.d/driver-only-hashes.txt
@@ -0,0 +1,10 @@
+Features
+   * All modules that use hashes or HMAC can now take advantage of PSA Crypto
+     drivers when MBEDTLS_PSA_CRYPTO_C is enabled and psa_crypto_init() has
+     been called. Previously (in 3.3), this was restricted to a few modules,
+     and only in builds where MBEDTLS_MD_C was disabled; in particular the
+     entropy module was not covered which meant an external RNG had to be
+     provided - these limitations are lifted in this version. A new set of
+     feature macros, MBEDTLS_MD_CAN_xxx, has been introduced that can be used
+     to check for availability of hash algorithms, regardless of whether
+     they're provided by a built-in implementation, a driver or both.