Clarify difference between `.load()` and `.compute()`

What is your issue?

I just realized that the difference between .load() and .compute() is that .load() operates inplace and .compute() returns a new xarray object.I have 2 suggestions for how this could be clearer:

1. Docs: the API docs for each method could reference the other.
2. Code: this might be too big a change, but maybe .load() should not return anything. Consider this example from pandas:

   import pandas as pd
   
   df = pd.DataFrame({"air": []})
   df.rename({"air": "foo"}, axis=1, inplace=True)
   # returns None since df is renamed inplace
   

   this matches the behavior of inplace actions in Python itself like list.append or dict.update. This would be a major breaking change though, and it might be easier to just remove .load() entirely.

Start with the API documentation for .load() and .compute() and compare their documented in-place and return-value behavior. Done means the two method docs cross-reference each other and clearly state the distinction; the proposed breaking API change is separate and needs a maintainer decision.