Avoid linking file paths inside backticks

[st0012]

Highlighting file paths like lib/foo/bar.rb should not be linked to the file automatically. If the writer's intention is to link it, rdoc-ref should be used.

[matzbot]

🚀 Preview deployment available at: https://2c9109b6.rdoc-6cd.pages.dev (commit: 3d94ce838966b18c29a0b7761dddd0d610b8fa40)