Fix children count mismatch and enhance query entry labeling

[Malcolmnixon]

This pull request introduces significant improvements to the clarity and usability of Markdown output generated by the SysML2Tools Query subsystem. The most important changes ensure that the describe verb and other query verbs now provide a more accurate and user-friendly summary and entries section: the child count in summaries always matches the number of visible, named children, and each entries table (or its absence) is clearly labeled with a verb-specific bold-text label. This makes reports easier to read and interpret, especially when there are zero results. Several new tests and documentation updates accompany these changes to guarantee correctness and document the new behavior.

Markdown Output Improvements:

• The entries table in Markdown output is now always preceded by a verb-specific bold-text label (e.g., **Children** for describe, **Uses** for uses), and when there are no entries, a verb-specific fallback message is shown (e.g., _No children._). This label is always plain bold text, never a Markdown heading, so the report remains in a single section. The dependencies verb remains an exception, using prose bullets without a label. [1] [2] [3] [4]

• For verbs without a specific label mapping, a generic **Entries** label and _No entries._ fallback are used, ensuring future verbs render sensibly. [1] [2]

Summary and Child Count Accuracy:

• The describe verb summary now reports a Children: N line where N is the count of visible, named children actually included in the entries table—never the raw count of AST child nodes. This prevents confusion when non-element children or hidden stdlib children are present but not listed. [1] [2] [3] [4]

Documentation and Requirements Updates:

• Documentation and requirements files (.md, .yaml) have been updated to describe the new Markdown output format, child count semantics, and rationale for these changes. This includes new or revised requirement sections and scenario/test documentation. [1] [2] [3] [4] [5]

Test Coverage:

• New and updated tests verify that the entries label and fallback messaging behave as expected for all verbs, that the label is always bold text (never a heading), and that the Children count matches the actual number of listed children. [1] [2] [3]

These changes collectively improve the clarity, correctness, and maintainability of query results, making them more intuitive for users and easier to embed in other documentation.