Adjust presence of warning/link.

- the codegen migration document is already a migration document, so
doesn't need the extra warning about work in progress;
- the driver interface can use a link to the more practical guide too.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

docs/proposed/psa-driver-interface.md

@@ -5,6 +5,8 @@ This document describes an interface for cryptoprocessor drivers in the PSA cryp
 
 This specification is work in progress and should be considered to be in a beta stage. There is ongoing work to implement this interface in Mbed TLS, which is the reference implementation of the PSA Cryptography API. At this stage, Arm does not expect major changes, but minor changes are expected based on experience from the first implementation and on external feedback.
 
+For a practical guide, with a description of the current state of drivers Mbed TLS, see our [PSA Cryptoprocessor driver development examples](../psa-driver-example-and-guide.html).
+
 ## Introduction
 
 ### Purpose of the driver interface