Add option to include ADR status in TOC

[samuelsuarezsanchez]

It would be ideal if we could include the status of each ADR in the table of contents.

The intended use is:

$ adr generate toc -s
# Architecture Decision Records

* [1. Record architecture decisions](0001-record-architecture-decisions.md): Accepted
* [2. Implement as shell scripts](0002-implement-as-shell-scripts.md): Accepted
* [3. Single command with subcommands](0003-single-command-with-subcommands.md): Accepted
* [4. Markdown format](0004-markdown-format.md): Accepted
* [5. Help comments](0005-help-comments.md): Amended by [9. Help scripts](0009-help-scripts.md)
* [6. Packaging and distribution in other version control repositories](0006-packaging-and-distribution-in-other-version-control-repositories.md): Accepted
* [7. Invoke adr-config executable to get configuration](0007-invoke-adr-config-executable-to-get-configuration.md): Accepted
* [8. Use ISO 8601 Format for Dates](0008-use-iso-8601-format-for-dates.md): Accepted
* [9. Help scripts](0009-help-scripts.md): Amends [5. Help comments](0005-help-comments.md)

I made the decision to only keep the last line under the Status section so that amendments are properly printed with their links.

[npryce]

Good idea, but I would appreciate some tests to help me keep it working in the future

[samuelsuarezsanchez]

@npryce I've managed to find time to add tests and to tweak these changes to make it work with links in the status (e.g. superceded).

[cfinnigan-nyshex]

@npryce any chance of getting this merged now that tests have been added?