Calm docify index.md doesn't point to other .md files in folders

## Bug Report

### Steps to Reproduce:
1. calm docify -a architecture.json -o docs/
2. index.md generated doesn't point to other .md files in nodes or relationships directory
3. VSCode is smart enough to navigate from index.md to other files under nodes/ or relationships/ directory but most non-developers use markdown viewer plugin in Chrome which will need relative path to the correct directories for each file like nodes/node1.md or relationships/relation1.md

### Expected Result:
Please make sure that the index.md generated file by calm docify command has the relative path to point to the correct files in the correct folders.

### Actual Result:
If I don't modify index.md manually, the markdown viewer plugin from Chrome browser, when clicked on any node or relationship link will say that "file not found"

### Environment:
Windows 11, Chrome browser, Markdown viewer plugin version 5.3 by Simov.GitHub.io

Run `calm docify -a architecture.json -o docs/` and inspect the generated `index.md` alongside the `nodes/` and `relationships/` files. Trace the docify command's index-link generation, then verify that links opened by a Chrome Markdown viewer resolve to the correct relative paths without manual edits.

Written by the indexing model from the issue text.