Update doc/specs/stdlib_logger.md

Co-authored-by: Jeremie Vandenplas <jeremie.vandenplas@gmail.com>

Author: milancurcic

doc/specs/stdlib_logger.md

@@ -243,25 +243,25 @@ to `unit`.
 ```fortran
 program demo_add_log_unit
     use stdlib_logger, only: global_logger, read_only_error
-     ...
+
      character(256) :: iomsg
      integer :: iostat, unit, stat
-     ...
+
      open( newunit=unit, 'error_log.txt',      &
           form='formatted', status='replace', &
           position='rewind', err=999,         &
           action='read', iostat=iostat, iomsg=iomsg )
-     ...
+
      call global_logger % add_log_unit( unit, stat )
      select case ( stat )
-     ...
+
      case ( read_only_error )
          error stop 'Unable to write to "error_log.txt".'
-     ...
+
      end select
-     ...
+
      999 error stop 'Unable to open "error_log.txt".
-     ...
+
 end program demo_add_log_unit
 ```