feat: add code-group title

[lavecoral]

Add same custom title as custom container to code group

[MarkusKeck]

Isn't this the same as #1834

It got added in the latest version 1.0.0-alpha.47 (2023-02-20)
https://github.com/vuejs/vitepress/blob/main/CHANGELOG.md

It is already documented on the vitepress website
https://vitepress.vuejs.org/guide/markdown#code-groups

[brc-dd]

@MarkusKeck No, this one adds something like a caption to a code-block:

I am still not sure if we'll be adding this though. For images this might make sense, but for code groups/blocks I don't think this has any use case.

[MarkusKeck]

@brc-dd Thanks for clarification, I also dont really see a usecase, if you want the whole filename you can just add it to the title.

[MarkusKeck]

@lavecoral Some of the tests have failed. You can check this manually before pushing:

pnpm check

If something is not formatted correctly run: prettier --check .
After that prettier --write <filename>

[lavecoral]

@brc-dd link that: https://docs.spring.io/spring-security/reference/migration/servlet/session-management.html