feat(cert-create): update for ECDSA brainpoolP256r/t1 support

Updated cert_tool to be able to select brainpool P256r/t1
or NIST prim256v1 curve for certificates signature.

Change-Id: I6e800144697069ea83660053b8ba6e21c229243a
Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@foss.st.com>
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 0b42a79..402de13 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -610,22 +610,28 @@
 
 -  ``KEY_ALG``: This build flag enables the user to select the algorithm to be
    used for generating the PKCS keys and subsequent signing of the certificate.
-   It accepts 3 values: ``rsa``, ``rsa_1_5`` and ``ecdsa``. The option
-   ``rsa_1_5`` is the legacy PKCS#1 RSA 1.5 algorithm which is not TBBR
-   compliant and is retained only for compatibility. The default value of this
-   flag is ``rsa`` which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
+   It accepts 5 values: ``rsa``, ``rsa_1_5``, ``ecdsa``, ``ecdsa-brainpool-regular``
+   and ``ecdsa-brainpool-twisted``. The option ``rsa_1_5`` is the legacy PKCS#1
+   RSA 1.5 algorithm which is not TBBR compliant and is retained only for
+   compatibility. The default value of this flag is ``rsa`` which is the TBBR
+   compliant PKCS#1 RSA 2.1 scheme.
 
 -  ``KEY_SIZE``: This build flag enables the user to select the key size for
    the algorithm specified by ``KEY_ALG``. The valid values for ``KEY_SIZE``
    depend on the chosen algorithm and the cryptographic module.
 
-   +-----------+------------------------------------+
-   |  KEY_ALG  |        Possible key sizes          |
-   +===========+====================================+
-   |    rsa    | 1024 , 2048 (default), 3072, 4096* |
-   +-----------+------------------------------------+
-   |   ecdsa   |            unavailable             |
-   +-----------+------------------------------------+
+   +---------------------------+------------------------------------+
+   |         KEY_ALG           |        Possible key sizes          |
+   +===========================+====================================+
+   |           rsa             | 1024 , 2048 (default), 3072, 4096* |
+   +---------------------------+------------------------------------+
+   |          ecdsa            |            unavailable             |
+   +---------------------------+------------------------------------+
+   |  ecdsa-brainpool-regular  |            unavailable             |
+   +---------------------------+------------------------------------+
+   |  ecdsa-brainpool-twisted  |            unavailable             |
+   +---------------------------+------------------------------------+
+
 
    * Only 2048 bits size is available with CryptoCell 712 SBROM release 1.
      Only 3072 bits size is available with CryptoCell 712 SBROM release 2.