[Bug] Opening a directory of Markdown files does not list files in the Notebooks list unless they contain headings

[fyodorovich]

Bug description:
Markdown files which do not use headings in the markdown are not displayed in the list of Noteboooks.
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Expected behaviour:
There should be some fallback for markdown files which don't include heading markup.

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Environment:

• MindForger version: MindForger 1.54.0
• Operating system: MacOS 13.6 (22G120)

Steps to reproduce 🐞:

1. Create a text file and format with markup without using headings.
2. Save and return to Mindforger
3. Use the menu or the icon to open a directory containing markup files.
4. Files that contain headings are listed in Notebooks. Files that do not are not listed.