Add SSL error code updates from #4724

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

docs/3.0-migration-guide.md

@@ -902,7 +902,7 @@ find themselves unable to migrate their session cache functionality without
 accessing fields of `mbedtls_ssl_session` should describe their use case
 on the Mbed TLS mailing list.
 
-### Removal of some SSL error codes
+### Changes in the SSL error code space
 
 This affects users manually checking for the following error codes:
 
@@ -929,9 +929,28 @@ Migration paths:
   compare the size of their own certificate against the configured size of the output buffer to
   understand if the error is due to an overly large certificate.
 
-- `MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN` and `MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE` have been replaced by `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`
+- `MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN` and `MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE` have been
+  replaced by `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`.
 
-- all codes of the form `MBEDTLS_ERR_SSL_BAD_HS_XXX` have been replaced by various alternatives.
+- All codes of the form `MBEDTLS_ERR_SSL_BAD_HS_XXX` have been replaced by various alternatives.
+
+  Users should check for the newly introduced generic error codes
+
+  * `MBEDTLS_ERR_SSL_DECODE_ERROR`
+  * `MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER`,
+  * `MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE`
+  * `MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION`
+  * `MBEDTLS_ERR_SSL_BAD_CERTIFICATE`
+  * `MBEDTLS_ERR_SSL_UNRECOGNIZED_NAME`
+  * `MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION`
+  * `MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL`
+
+  and the pre-existing generic error codes
+
+  * `MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE`
+  * `MBEDTLS_ERR_SSL_INTERNAL_ERROR`
+
+  instead.
 
 ### Modified semantics of `mbedtls_ssl_{get,set}_session()`