Explain the changes to configure
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Nikola Pajkovsky <nikolap@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/29338)
### Changes between 3.6 and 4.0 [xx XXX xxxx]
+ * Removed configure options can now only be disabled. You may continue to use
+ `disable-<feature>`, which will remain supported. Using `enable-<feature>`
+ for a removed feature is no longer permitted.
+
+ *Andrew Dinh*
+
* Support for SSLv3 was removed. SSLv3 has been deprecated since
2015, and OpenSSL had it disabled by default since 1.1.0 (2016).