docs: clarify short-term memory behavior in the memory example

[azarboon]

Description

What changed:
This change clarifies that the memory used in the memory agent workflow is short-term, using the same terminology as the mem0 documentation, and is scoped to the current session by default. It also directs users to the relevant configuration and documentation for enabling persistence across sessions. Links to the appropriate mem0 documentation are added to improve discoverability and navigation.

Why this change is needed:
The current documentation is largely silent and somewhat misleading regarding memory persistence. This ambiguity is compounded by the fact that mem0’s own documentation is vague on this topic. I had to spend time verifying the actual behavior, and this change aims to save that effort for future readers. The updated text aligns expectations with the default behavior and provides clear pointers to configuration options for enabling persistence.

Related Issues

Type of Change

• New content
• Content update/revision

Checklist

• I have read the CONTRIBUTING document
• My changes follow the project's documentation style
• I have tested the documentation locally using mkdocs serve
• Links in the documentation are valid and working

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