Fix notes for lost braces check on CRAN

[villegar]

Version: 1.0.5
Check: Rd files
Result: NOTE 
  checkRd: (-1) bvp.Rd:24: Lost braces
      24 | differential equations.  The code{midptivp} method solves initial
         |                                  ^
  checkRd: (-1) ivp.Rd:38: Lost braces
      38 | differential equations.  The code{midptivp} method solves initial
         |                                  ^
  checkRd: (-1) ivpsys.Rd:29: Lost braces
      29 | differential equations.  The code{midptivp} method solves initial
         |                                  ^
Flavors: [r-devel-linux-x86_64-debian-clang](https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-debian-clang/cmna-00check.html), [r-devel-linux-x86_64-debian-gcc](https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-debian-gcc/cmna-00check.html), [r-devel-linux-x86_64-fedora-clang](https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-fedora-clang/cmna-00check.html), [r-devel-linux-x86_64-fedora-gcc](https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-fedora-gcc/cmna-00check.html), [r-devel-windows-x86_64](https://www.r-project.org/nosvn/R.check/r-devel-windows-x86_64/cmna-00check.html), [r-patched-linux-x86_64](https://www.r-project.org/nosvn/R.check/r-patched-linux-x86_64/cmna-00check.html), [r-release-linux-x86_64](https://www.r-project.org/nosvn/R.check/r-release-linux-x86_64/cmna-00check.html), [r-release-macos-arm64](https://www.r-project.org/nosvn/R.check/r-release-macos-arm64/cmna-00check.html), [r-release-macos-x86_64](https://www.r-project.org/nosvn/R.check/r-release-macos-x86_64/cmna-00check.html), [r-release-windows-x86_64](https://www.r-project.org/nosvn/R.check/r-release-windows-x86_64/cmna-00check.html), [r-oldrel-macos-arm64](https://www.r-project.org/nosvn/R.check/r-oldrel-macos-arm64/cmna-00check.html), [r-oldrel-macos-x86_64](https://www.r-project.org/nosvn/R.check/r-oldrel-macos-x86_64/cmna-00check.html), [r-oldrel-windows-x86_64](https://www.r-project.org/nosvn/R.check/r-oldrel-windows-x86_64/cmna-00check.html)