doc: Updated user guide with new Mbed TLS version number

Signed-off-by: zelalem-aweke <zelalem.aweke@arm.com>
Change-Id: Ib12ecc0b283274c74cdfa57caf9e1a105dce3afe

docs/getting_started/user-guide.rst

@@ -1154,7 +1154,7 @@ images with support for these features:
    is important to use a version that is compatible with TF-A and fixes any
    known security vulnerabilities. See `mbed TLS Security Center`_ for more
    information. The latest version of TF-A is tested with tag
-   ``mbedtls-2.16.0``.
+   ``mbedtls-2.16.2``.
 
    The ``drivers/auth/mbedtls/mbedtls_*.mk`` files contain the list of mbed TLS
    source files the modules depend upon.