id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
852256995,MDU6SXNzdWU4NTIyNTY5OTU=,5125,Add `BackendEntrypoint` to an easier to find location,226037,closed,0,,,3,2021-04-07T10:21:16Z,2021-04-11T18:53:03Z,2021-04-11T18:53:03Z,MEMBER,,,,"**Is your feature request related to a problem? Please describe.**

I started implementing a few backend plugins following the documentation so I noticed a few easily fixable quirks:

http://xarray.pydata.org/en/latest/internals/how-to-add-new-backend.html

The main one is the `BackendEntrypoint` is found deep into `xarray.backends.common`.

**Describe the solution you'd like**

I suggest to add an easier to find reference:
* `xarray.backends.BackendEntrypoint` would do
* but maybe even `xarray.BackendEntrypoint`. 

**Additional context**

For the simplest plugins `BackendEntrypoint` would be the only import to connect to *xarray*.

See this dummy GDAL plugin: https://github.com/bopen/xarray-gdal/blob/main/xarray_gdal/xarray_plugin.py
But also the *rioxarray* plugin in this PR: corteva/rioxarray/pull/281","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5125/reactions"", ""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue