Update dataset rename + api ref updates

[FayazRahman]

🚀 🚀 Pull Request

Checklist:

• My code follows the style guidelines of this project and the Contributing document
• I have commented my code, particularly in hard-to-understand areas
• I have kept the coverage-rate up
• I have performed a self-review of my own code and resolved any problems
• I have checked to ensure there aren't any other open Pull Requests for the same change
• I have described and made corresponding changes to the relevant documentation
• New and existing unit tests pass locally with my changes

Changes

Make rename and copy show up in docs.
Add examples for dataset renames.
Check if new path is empty while renaming datasets.

[codecov]

Codecov Report

Merging #1566 (bf3246b) into main (163483c) will increase coverage by 0.06%.
The diff coverage is 96.15%.

@@            Coverage Diff             @@
##             main    #1566      +/-   ##
==========================================
+ Coverage   92.36%   92.43%   +0.06%     
==========================================
  Files         199      199              
  Lines       17950    17970      +20     
==========================================
+ Hits        16580    16611      +31     
+ Misses       1370     1359      -11     

Flag	Coverage Δ
unittests	92.43% <96.15%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
hub/__init__.py	94.11% <ø> (ø)
hub/api/dataset.py	90.86% <ø> (ø)
hub/util/exceptions.py	81.84% <75.00%> (+0.73%)	⬆️
hub/api/tests/test_api.py	100.00% <100.00%> (ø)
hub/core/dataset/dataset.py	93.11% <100.00%> (+0.37%)	⬆️
hub/core/dataset/hub_cloud_dataset.py	90.76% <100.00%> (+0.07%)	⬆️
hub/core/storage/gcs.py	75.00% <100.00%> (+0.35%)	⬆️
hub/core/storage/local.py	94.11% <100.00%> (+0.14%)	⬆️
hub/core/storage/s3.py	69.82% <100.00%> (+0.64%)	⬆️
... and 3 more

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