Fix the CRAN checking NOTE

[LittleBeannie]

• checking Rd line widths ... NOTE
  Rd file 'gs_cp.Rd':
  \examples lines wider than 100 characters:
  gs_cp(x = x, theta = c(0.15, 0.2, 0.25, 0.3), i = 1, zi = -gsDesign::hrn2z(hr = 0.8, n = 150+180, ratio = 1))

Rd file 'gs_cp_simple.Rd':
\examples lines wider than 100 characters:
# Calculate conditional power with optional user-input theta (if NULL, will come from the input design)