Docs: Interactivity API - Rename "API Reference" to "Directives and Store API Reference"

[juanmaguitar]

After moving Interactivity API docs to Block Editor Handbook > Reference Guides > Interactivity API Reference, the structure of this sections is as follows:

• Interactivity API Reference
  • Quick start guide
  • API Reference

As the word "Reference" will be kept for now (see #60782) for any subpage below Reference Guides, with the current structure, it may be a bit confusing having "Interactivity API Reference" and "API Reference" different pages on the same section.

Also, as per the current issue with docs generation explained at #61206 having an api-reference.md file may cause conflict in the future with any other api-reference.md file under any other section.

To solve this situation, I suggest the following actions:

• Change the title of "API Reference" to "Directives and Store API Reference"
• Change the filename to directives-store-api-reference.md

This change would require a redirection.

Another option could be to simply remove the "Reference" word from "Interactivity API Reference", but this would go against the rule followed by the rest of subsections under Reference Guides

cc: @ndiego @cbravobernal @sirreal @luisherranz