Correct display of embracing operator

[capnrefsmmat]

Quarto supports inline code using the backtick operator 1, using backticks and curly quotes to specify the engine. Because of this, {{ }} is apparently parsed as inline code and renders as { }. An extra level of curly braces must be added to display the embracing operator in the text.

(I suppose this could also be considered a Quarto bug, since their parser is treating this as inline code when it clearly isn't. But this is an easy solution.)