Add destroy_from_vectorsearch hook

[andreibondarev]

Related to #53

Introduces the destroy_from_vectorsearch hook and updates documentation to support record deletion in vectorsearch databases.

• Adds a destroy_from_vectorsearch method in lib/langchainrb_rails/active_record/hooks.rb to handle the deletion of records from vectorsearch databases. This method is designed to be called within an after_destroy callback.
• Implements an after_destroy :destroy_from_vectorsearch callback within the same file to ensure records are automatically removed from the vectorsearch database upon deletion.
• Updates the README.md file to include a new section on handling record deletions with the destroy_from_vectorsearch hook, providing users with guidance on how to use this feature effectively.

---

For more details, open the Copilot Workspace session.