add comment regarding ord_sort

Author: jvdp1

doc/specs/stdlib_stats.md

@@ -202,7 +202,7 @@ and if `n` is an odd number, the median is:
 median(array) = mean( array_sorted( floor( (n + 1) / 2.):floor( (n + 1) / 2.) + 1 ) )
 ```
 
-The array is sorted using the subroutine `sort` provided by the `stdlib_sorting`
+The array is sorted using the subroutine `ord_sort` provided by the `stdlib_sorting`
 module.
 
 ### Syntax

src/stdlib_stats_median.fypp

@@ -8,6 +8,9 @@ submodule (stdlib_stats) stdlib_stats_median
   use, intrinsic:: ieee_arithmetic, only: ieee_value, ieee_quiet_nan
   use stdlib_error, only: error_stop
   use stdlib_optval, only: optval
+  ! Use "ord_sort" rather than "sort" because the former can be much faster for arrays
+  ! that are already partly sorted. While it is slightly slower for random arrays,
+  ! ord_sort seems a better overall choice.
   use stdlib_sorting, only:sort => ord_sort
   implicit none