[DOCS] Add a note about inference endpoint creation to the hybrid search tutorial

[kosabogi]

Based on @szabosteve's comment on the hybrid search tutorial PR: #114398 (comment)

Add a note in the hybrid search tutorial regarding the automatic creation of an inference endpoint when using the 'semantic_text' field.
The default service for 'semantic_text' will be ELSER, which means that users do not need to manually create an inference endpoint when they create an index with a 'semantic_text' field.

The tutorial currently includes steps for manually creating an inference endpoint. The note should contain that it is only for demonstrating how the process works, especially for users who may need to use a different service.

This update should be implemented once the feature becomes publicly available.