Enable Automatic Section Name Retrieval in toc.yaml

[martyanovandrey]

Description
Enhance the toc.yaml functionality by enabling automatic retrieval of section names from the first-level heading (# Heading in Markdown) of the file specified in the href, if the name is not provided.

Proposed Enhancement

• Modify the logic to fetch the section name directly from the file when name is absent.

Benefits

• Reduces redundancy and streamlines the documentation process.
• Ensures consistency by automatically reflecting titles from the files.

Acceptance Criteria

• Sections in toc.yaml without a name use the first-level heading from the href file.
• Update documentation and examples to demonstrate this feature.
• Add tests to verify the feature works correctly and does not impact existing functionality.

Additional Notes

• Define fallback behavior if the file lacks a first-level heading.
• Consider performance impacts in large projects.

Entry point for development
https://github.com/diplodoc-platform/cli/blob/master/src/services/tocs.ts