Update Readme with updated examples

[Calemy]

Description
There have been some changes made to the meilisearch-go api. One of them including what type is being used to update the filterable attributes. Instead of strings, we now use an interface array, which is not reflected on the README and can be therefore confusing to beginners.

Basic example

task, err := index.UpdateFilterableAttributes(&[]string{"id", "genres"})

would become

task, err := index.UpdateFilterableAttributes(&[]any{"id", "genres"})
//I am aware it's an interface, but any is just a reference to interface anyways.

While i'm not sure how many routes have been affected, updating the docs is crucial to not frustrate unaware developers.

[ElyarSadig]

According to the docs, filterableAttributes can be an array of either strings or filterable attribute objects. It was updated to []interface{} to cover both options. Since there is already an example in .code-samples.meilisearch.yaml, I believe it would be beneficial to add another example to demonstrate the use of filterable attribute objects as well.

[Calemy]

as far as i'm concerned, the go compiler throws a fit if i try to assign it a string array!