Changing the migration guide entry wording.

Signed-off-by: TRodziewicz <tomasz.rodziewicz@mobica.com>
diff --git a/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md b/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md
index 8484dfb..4c87f03 100644
--- a/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md
+++ b/docs/3.0-migration-guide.d/remove_supp_for_extensions_in_pre-v3_X_509_certs.md
@@ -1,11 +1,14 @@
 Remove the `MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3` option
 --
 
-This change does not affect users who are working with current V3 X.509
-certificates.
+This change does not affect users who were using the default configuration, as
+this option was already disabled by default. Also, it does not affect users who
+are working with current V3 X.509 certificates.
 
-This change makes the pre-V3 X.509 certificates both with or without optional
-extensions obsolete.
+Extensions were added in V3 of the X.509 specification, so pre-V3 certificates
+containing extensions were never compliant. Mbed TLS now rejects them with a
+parsing error in all configurations, as it did previously in the default
+configuration.
 
 If you are working with the pre-V3 certificates you need to switch to the
 current ones.