[V2] Custom frontmatter/metadata is no longer available

🐛 Bug Report

Custom frontmatter/metadata defined in markdown files is no longer accessible within the DocItem component when it previously was.

It appears this change broke the behavior.

Have you read the Contributing Guidelines on issues?

Yes

To Reproduce

1. Add a custom frontmatter field in a blog post or documentation markdown file.
2. The property is no longer available in this object.

Expected behavior

Frontmatter, by nature, should allow for a variety of keys, especially a platform designed to serve a variety of different project types.

[yangshun]

@binarylogic We would discourage swizzling components at this point until we reach beta or even 2.0.0 for this very reason. Apologies for the changes.

[binarylogic]

Thanks, I must have been using an older version of DocItem/index.js because the frontMatter definition was not included.