Update documentation to address CRAN notes

[villegar]

CRAN notes

Version: 2.0.0
Check: Rd files
Result: NOTE 
  checkRd: (-1) add_legend.Rd:59: Lost braces; missing escapes or markup?
      59 | Use `add_legend()` to place a legend below a {reactable} table.
         |                                              ^
  checkRd: (-1) add_source.Rd:77: Lost braces; missing escapes or markup?
      77 | Use `add_source()` to place a source below a {reactable} or {reactablefmtr} table.
         |                                              ^
  checkRd: (-1) add_source.Rd:77: Lost braces; missing escapes or markup?
      77 | Use `add_source()` to place a source below a {reactable} or {reactablefmtr} table.
         |                                                             ^
  checkRd: (-1) add_subtitle.Rd:77: Lost braces; missing escapes or markup?
      77 | Use `add_subtitle()` to place a subtitle above a {reactable} or {reactablefmtr} table.
         |                                                  ^
  checkRd: (-1) add_subtitle.Rd:77: Lost braces; missing escapes or markup?
      77 | Use `add_subtitle()` to place a subtitle above a {reactable} or {reactablefmtr} table.
         |                                                                 ^
  checkRd: (-1) add_title.Rd:76: Lost braces; missing escapes or markup?
      76 | Use `add_title()` to place a title above a {reactable} or {reactablefmtr} table.
         |                                            ^
  checkRd: (-1) add_title.Rd:76: Lost braces; missing escapes or markup?
      76 | Use `add_title()` to place a title above a {reactable} or {reactablefmtr} table.
         |                                                           ^
  checkRd: (-1) bubble_grid.Rd:135: Lost braces; missing escapes or markup?
     135 |     The format of the numbers within the bubbles can be changed by defining the format from a package such as the {scales} package within `number_fmt`.
         |                                                                                                                   ^
  checkRd: (-1) cell_style.Rd:88: Lost braces; missing escapes or markup?
      88 | Use `cell_style()` to customize the appearance of certain cells in a {reactable} or {reactablefmtr} table.
         |                                                                      ^
  checkRd: (-1) cell_style.Rd:88: Lost braces; missing escapes or markup?
      88 | Use `cell_style()` to customize the appearance of certain cells in a {reactable} or {reactablefmtr} table.
         |                                                                                     ^
  checkRd: (-1) cell_style.Rd:93: Lost braces; missing escapes or markup?
      93 |      Some options within `cell_style()` will work with other {reactablefmtr} formatters (such as data_bars() and color_tiles()),
         |                                                              ^
  checkRd: (-1) cell_style.Rd:26: Lost braces; missing escapes or markup?
      26 | \item{data}{A dataset to be displayed within a {reactable} table.}
         |                                                ^
  checkRd: (-1) group_border_sort.Rd:6: Lost braces; missing escapes or markup?
       6 | Credit to Greg Lin, creator of {reactable} for writing the JS function.}
         |                                ^
  checkRd: (-1) group_border_sort.Rd:41: Lost braces; missing escapes or markup?
      41 | Credit to Greg Lin, creator of {reactable} for writing the JS function.
         |                                ^
  checkRd: (-1) group_merge_sort.Rd:6: Lost braces; missing escapes or markup?
       6 | Credit to Greg Lin, creator of {reactable} for writing the JS function.}
         |                                ^
  checkRd: (-1) group_merge_sort.Rd:18: Lost braces; missing escapes or markup?
      18 | Credit to Greg Lin, creator of {reactable} for writing the JS function.
         |                                ^
  checkRd: (-1) react_sparkbar.Rd:127: Lost braces; missing escapes or markup?
     127 | The `react_sparkbar()` function utilizes the {dataui} package <https://github.com/timelyportfolio/dataui> to create an interactive sparkline bar chart.
         |                                              ^
  checkRd: (-1) react_sparkline.Rd:147: Lost braces; missing escapes or markup?
     147 | The `react_sparkline()` function utilizes the {dataui} package <https://github.com/timelyportfolio/dataui> to create an interactive sparkline line chart.

Context

This task was proposed by R Core developer Kurt Hornik as part of an initiative to improve CRAN package documentation. Packages with public repositories (GitHub, GitLab, Bitbucket) and a higher number of reverse dependencies were prioritised. This PR has been completed as part of an R Dev Day at the University of Warwick on 12 Sept 2025 (see r-devel/r-dev-day#110).