Fix typo

[akazeakari]

Description

Fix typo in documents.

Motivation and Context

The word 'initiaiton' should be spelled as 'initiation'. Moreover, in this context, the code's function is to set initial parameters or states for the model or dataset, so the term 'initialization' is more accurate.

'model initiaiton' or 'model initiation' -> 'model initialization'
'dateset' -> 'dataset'

How Has This Been Tested?

• Pass the test by running: pytest qlib/tests/test_all_pipeline.py under upper directory of qlib.
• If you are adding a new feature, test on your own test scripts.

Screenshots of Test Results (if appropriate):

1. Pipeline test:
2. Your own tests:

Types of changes

• Fix bugs
• Add new feature
• Update documentation

[you-n-g]

Thanks for your great efforts.