Rd file markup issue

[RobinHankin]

checking R code for possible problems ... [19s/33s] OK
checking Rd files ... [3s/5s] NOTE
checkRd: (-1) Ops.hyper2.Rd:48: Lost braces; missing escapes or markup?
    48 |   Idiom \code{H1-H1} returns {H1 + (-1)*H2}, useful for investigating
       |                              ^
checkRd: (-1) eurodance.Rd:37: Lost braces
    37 |     2009---{Wikipedia}{,} The Free Encyclopedia}, 2018,
       |                       ^
checkRd: (-1) eurovision.Rd:45: Lost braces
    45 |     2009---{Wikipedia}{,} The Free Encyclopedia}, 2018,
       |                       ^
checkRd: (-1) formula1.Rd:56: Lost braces
    56 |     Championship---{Wikipedia}{,} The Free Encyclopedia}, 2018.
       |                               ^
checkRd: (-1) pentathlon.Rd:30: Lost braces
    30 |     Summer Olympics - Men's}.  {Wikipedia}{,} The Free Encyclopedia,
       |                                           ^
checking Rd metadata ... OK