docs: fix Image.from_file() to use keyword-only parameter

[budisteanualexandra]

This PR fixes incorrect usage of Image.from_file() in the documentation and examples.

Changes

• Updated README examples to use the keyword argument.
• Updated reStructuredText documentation examples.
• Updated example usages in models.py to reflect the correct API.

Following the previous documentation resulted in TypeError exceptions when calling
Image.from_file() with positional arguments. This change aligns the examples with
the actual SDK behavior.

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[sararob]

Thanks for this PR! The models.py and index.rst.txt files are autogenerated. Could you revert the changes to those files and we'll merge in your readme update?