DocLink failed to link /cpp/language/basic_concepts/modules

[Sudrut]

[Sudrut]

DocLink cannot link pages without a key, but we use absolute paths now and don't need "keys" anymore.

[frederick-vs-ja]

I don't think it should link to /cpp/language/basic_concepts/modules, let's fix the link.

[Sudrut]

I don't think it should link to /cpp/language/basic_concepts/modules, let's fix the link.

I edited the example so it's more related to "module".

I don't know whether we should provide a key property at the top of the file /src/content/docs/cpp/language/basic_concepts/modules.mdx like "cpp.lang.basic.modules", or change how DocLink works so it can link to all doc pages without specifiying a key.