Added classic_policy_set parameter to the Create project API endpoint

Ticket: ENT-12436
Signed-off-by: Ihor Aleksandrychiev <ihor.aleksandrychiev@northern.tech>

Author: aleksandrychev

api/enterprise-api-ref/build-api.markdown

@@ -39,6 +39,8 @@ A project is a set of CFEngine Build modules and custom files/json/policy files.
 * **sshKeyId** *(integer)*
   Generated SSH private key ID by [SSH keys API][SSH keys API#Generate SSH key] for authentication to the repository.
   Required when authentication type is `private_key` and `sshPrivateKey` is not set.
+* **classic_policy_set** *(boolean)*
+  The flag that indicates whether the build project is classic policy set (not cfbs) or not.
 
 **Note:** the SSH key is expected to be in openssh(rfc4716) format as generated by [SSH Keys API][SSH keys API#Generate SSH key] or a command line like: