Feature: markdown indexing

[nao1215]

Is your feature request related to a problem? Please describe.

The spectest produces reports in Markdown format on a per-test-case basis. It is hard for us to find the desired report among many Markdowns.

Therefore, we will add a function to index markdowns located under the specified directory.

Describe the solution you'd like

jbrown1618/markdown-index is close to the function we are looking for. However, some features are missing.

For example,

• change generating file name.
• change index markdown title
• change url text (now, it is same as file name)

Additional context

This feature will implement as cli command. In addition, add the ability to generate indexes with go generate.

[nao1215]

I am in the process of implementing it.

[nao1215]

I implemented GenerateIndex() in markdown package. See https://github.com/go-spectest/markdown/pull/8

I will implement index subcommand. (use GenerateIndex())

[nao1215]

Done https://github.com/go-spectest/spectest/pull/166