Fix/update doc

[madtoinou]

Checklist before merging this PR:

• Mentioned all issues that this PR fixes or addresses.
• Summarized the updates of this PR under Summary.
• Added an entry under Unreleased in the Changelog.

Fixes #2234, fixes #2276, fixes #2487, fixes #2193.

Summary

• Indicate that multi_lags=False will induce a shift of the lags for each step in output_chunk_length
• Added reference to timeseries_generation.datetime_attribute_timeseries in TimeSeries.add_datetime_attribute (reflect change of behavior; every encoding is now 0-indexed)
• Update the examples to reflect the deprecation of num_loader_workers and the introduction of kwargs_dataloader.
• Made CrostonModel a LocalForecastingModel instead of a FutureCovariatesLocalFM since the future covariates are actually leveraged only when conformal prediction is used, updated the table of models accordingly
• Added a new issue template for questions about documentation or features

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.78%. Comparing base (3e893cd) to head (b3b874e).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2511      +/-   ##
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- Coverage   93.80%   93.78%   -0.02%     
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  Files         139      139              
  Lines       14742    14727      -15     
==========================================
- Hits        13828    13812      -16     
- Misses        914      915       +1     

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[dennisbader]

Looks great @madtoinou. Thanks a lot for the fixes :) Only some minor comments