adr generate toc

[koppor]

adr-log uses a different ouptut - https://github.com/adr/adr-log#printing-the-adr-log-to-stdout

- [ADR-0000](0000-example-1.md) - Example 1
- [ADR-0001](0001-example-2.md) - Example 2
- [ADR-0002](0002-example-3.md) - Example 3

When adr generate toc is executed in markdown mode, it should also provide such a TOC and not:

* [Use Markdown Architectural Decision Records](0000-use-markdown-architectural-decision-records.md)
* [Use CC0 as license](0001-use-CC0-as-license.md)
* [Do not use numbers in headings](0002-do-not-use-numbers-in-headings.md)
* [Inlucde in adr-tools](0003-include-in-adr-tools.md)
* [Write own TOC tool](0004-write-own-toc-tool.md)