Add Changelog and documentation
Signed-off-by: Felix Conway <felix.conway@arm.com>
diff --git a/ChangeLog.d/unify-errors.txt b/ChangeLog.d/unify-errors.txt
new file mode 100644
index 0000000..3dad7f3
--- /dev/null
+++ b/ChangeLog.d/unify-errors.txt
@@ -0,0 +1,8 @@
+API changes
+ * Make the following error codes aliases of their PSA equivalents, where
+ xxx is a module, e.g. X509 or SSL.
+ MBEDTLS_ERR_xxx_BAD_INPUT_DATA -> PSA_ERROR_INVALID_ARGUMENT
+ MBEDTLS_ERR_xxx_ALLOC_FAILED -> PSA_ERROR_INSUFFICIENT_MEMORY
+ MBEDTLS_ERR_xxx_VERIFY_FAILED -> PSA_ERROR_INVALID_SIGNATURE
+ MBEDTLS_ERR_xxx_INVALID_SIGNATURE -> PSA_ERROR_INVALID_SIGNATURE
+ MBEDTLS_ERR_xxx_BUFFER_TOO_SMALL -> PSA_ERROR_BUFFER_TOO_SMALL