Support for `.razor` files is unclear

It's not listed here https://codeql.github.com/docs/codeql-overview/supported-languages-and-frameworks/#languages-and-compilers

But I also found no open issue requesting it be added which seems strange due to its popularity which leads me to believe support is bundled under the `.cshtml` file support?

Start with the supported-languages-and-frameworks documentation linked in the issue and check how `.cshtml` support is described. Determine whether `.razor` files are covered by that support, then clarify the documentation so the status of `.razor` files is explicit.

索引モデルが issue の本文から書いたものです。