x509: Reworded documentation bits.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index fc1d0bc..1ce0d23 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -922,7 +922,7 @@
  * \param[in] crt       Certificate to be queried, must not be \c NULL
  *
  * \return              \c 1 if this a CA certificate \c 0 otherwise.
- * \return              MBEDTLS_ERR_X509_INVALID_EXTENSIONS if the certificate does not support
+ * \return              MBEDTLS_ERR_X509_INVALID_EXTENSIONS if the certificate does not contain
  *                      the Optional Basic Constraint extension.
  *
  */