x/pkgsite: description of x/debug repo at golang.org/pkg page is outdated

[hyangah]

Here, the 'x/debug' repo is listed as a repo for 'an experimental debugger for Go'.
This is outdated. Please update the repo description and this documentation.

[dmitshur]

Thanks for reporting.

This needs to be updated in two places at this time:

• In x/build/repos: repos.go#L70. (Optional; can be updated later during resolution of x/website/_content: consider reusing repo list from x/build/repos instead of maintaining own hard-coded copy #36136.)
• In x/website/content/static: packageroot.html#L126.

After #36136 is resolved, only x/build/repos will need to be updated.