Update paramsSerializer Documentation to Include Object Assignment with serialize and encode Fields

[Gn0lee]

Describe the bug
The current axios documentation on paramsSerializer is insufficient and does not cover the new method of assigning an object with serialize and encode fields. This omission leads to confusion as users cannot specify custom encoding when they assign a function to paramsSerializer, as it defaults to axios’ basic encoding.

To Reproduce
Steps to reproduce the behavior:

1. Refer to the current axios documentation on paramsSerializer.
2. Assign a function to paramsSerializer in the axios configuration.
3. Attempt to define custom encoding.
4. Observe that the documentation does not explain how to properly assign paramsSerializer as an object with serialize and encode fields, leading to the issue where custom encoding cannot be specified.

Expected behavior
The documentation should clearly explain that paramsSerializer needs to be assigned an object containing serialize and encode fields. This change should be highlighted to ensure users understand how to specify custom encoding correctly.

Screenshots

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Additional context
To improve the documentation, a section should be added demonstrating the correct usage of paramsSerializer with an object. This should include examples and explanations of the serialize and encode fields, emphasizing the difference from the previous method of assigning a function directly. This update will help prevent confusion and ensure proper implementation of custom encoding.