Typo in documentation for registration of custom backend

[HertugHelms]

What happened?

Minor issue, but the documentation for the pyproject.toml version of packaging your custom backend has the entry point as "xarray-backends" where it should be "xarray.backends".
https://docs.xarray.dev/en/latest/internals/how-to-add-new-backend.html

I have created a pull request for the typo

What did you expect to happen?

I expected my custom engine to be discovered by xarray.backends.list_engines() but it didn't work.

Minimal Complete Verifiable Example

No response

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None
python: 3.11.7 (main, Dec 19 2023, 20:42:30) [GCC 10.2.1 20210110]
python-bits: 64
OS: Linux
OS-release: 5.15.133.1-microsoft-standard-WSL2
machine: x86_64
processor:
byteorder: little
LC_ALL: None
LANG: C.UTF-8
LOCALE: ('en_US', 'UTF-8')
libhdf5: 1.12.2
libnetcdf: 4.9.3-development

xarray: 2024.1.0
pandas: 2.2.0
numpy: 1.26.3
scipy: None
netCDF4: 1.6.5
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: None
cftime: 1.6.3
nc_time_axis: None
iris: None
bottleneck: None
dask: None
distributed: None
matplotlib: None
cartopy: None
seaborn: None
numbagg: None
fsspec: None
cupy: None
pint: None
sparse: None
flox: None
numpy_groupies: None
setuptools: 69.0.3
pip: 23.3.2
conda: None
pytest: 7.4.4
mypy: None
IPython: 8.20.0
sphinx: None
/usr/local/lib/python3.11/site-packages/_distutils_hack/init.py:33: UserWarning: Setuptools is replacing distutils.
warnings.warn("Setuptools is replacing distutils.")

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