:"To the compiler, the double-dash is treated as end-of-line, allowing continued parsing of the language as a context-free grammar."
is not really correct; if it were, the text of the comment would be parsed as language text. It would be more accurate to say that the double-dash causes the input parser to discard all characters until the end-of-line.
It's also not strictly true that comments can be nested, because the end-of-comment character is the EOL, and enclosing a comment in another does not require two EOLs (as it would if it were truly nested). But the intent is clear and I can't think of a wording that would be clearer.
Best wishes [[User:SimonTrew|Si Trew]] ([[User talk:SimonTrew|talk]]) 07:59, 19 September 2013 (UTC)