use public dtype module for docs instead of special-casing the core dype module

Author: d-v-b

docs/conf.py

@@ -51,7 +51,7 @@
 issues_github_path = "zarr-developers/zarr-python"
 
 autoapi_dirs = ['../src/zarr']
-autoapi_add_toctree_entry = True
+autoapi_add_toctree_entry = False
 autoapi_generate_api_docs = True
 autoapi_member_order = "groupwise"
 autoapi_root = "api"