sync spec & code (#107)

* sync spec & code

* move primitives (merkletree) into the backend

* comment on the ops spec and link to issue #108

* typo

* fix github-ci mdbook-publish pages

src/backends/plonky2/mock_signed.rs

@@ -2,12 +2,12 @@ use anyhow::Result;
 use std::any::Any;
 use std::collections::HashMap;
 
+use super::primitives::merkletree::MerkleTree;
 use crate::constants::MAX_DEPTH;
 use crate::middleware::{
     containers::Dictionary, hash_str, AnchoredKey, Hash, Params, Pod, PodId, PodSigner, PodType,
     Statement, Value, KEY_SIGNER, KEY_TYPE,
 };
-use crate::primitives::merkletree::MerkleTree;
 
 pub struct MockSigner {
     pub pk: String,