Unintuitive error

The error on missed `&` in the `access` method is very bloated and a little hard to read. This is not something that has to change, but I figured it's better to note it here.

```diff
+ let cw_storage = CwStorage(deps.storage);
+ let admins = ADMINS.access(&cw_storage).get()?;
- let cw_storage = CwStorage(deps.storage);
- let admins = ADMINS.access(cw_storage).get()?;
```

When the reference is omitted the error is as follows:

```shell
error[E0599]: the method `get` exists for struct `ItemAccess, StorageBranch>>`, but its trait bounds were not satisfied
--> src/contract.rs:54:48
|
54 | let admins = ADMINS.access(cw_storage).get();
| ^^^ method cannot be called due to unsatisfied trait bounds
|
::: /home/jan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/storey-0.3.0/src/storage/branch.rs:23:1
|
23 | pub struct StorageBranch {
| --------------------------- doesn't satisfy `_: StorageBackend` or `_: Storage`
|
= note: the following trait bounds were not satisfied:
`storey::storage::branch::StorageBranch>: storey_storage::backend::StorageBackend`
which is required by `storey::storage::branch::StorageBranch>: storey_storage::storage::Storage`
```

Start by reproducing the omitted-reference error at the ADMINS.access(cw_storage).get() call in src/contract.rs, then inspect the access method involved. The issue does not define a required fix, so agree on the desired diagnostic or behavior before making changes.

Written by the indexing model from the issue text.