The --one-file flag does not interpret Markdown by default in the README.md file (I have not checked other non-source files).

Steps to reproduce

1. Run the following commands:

cat << EOF >> foo.rb
# Foobar
# * asd
class Foo
end
EOF

cat << EOF >> README.md
# Foo
EOF

yard doc --one-file --no-save -o . foo.rb

2. Open the generated index.html in the browser

Actual Output

The Markdown in the README.md has not been interpreted.

Notice how # Foo is output from the README.md, but the Markdown in the foo.rb file has been interpreted and output as expected.

Expected Output

I expect the Markdown to be interpreted, this is what happens without the --one-file flag:

Environment details:

• OS: macOS 12.0.1
• Ruby version (ruby -v): ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-darwin20]
• YARD version (yard -v): yard 0.9.27