docs(stdlib_io): Add an example to show the brief mode of print_array

Author: zoziha

doc/specs/stdlib_io.md

@@ -343,6 +343,10 @@ that shows only the representative portions of large arrays, which is useful for
 
 ### Example
 
+```fortran
+{!./example/io/example_print_array_brief.f90}
+```
+
 ```fortran
 {!./example/io/example_print_array.f90}
 ```

example/io/CMakeLists.txt

@@ -7,3 +7,4 @@ ADD_EXAMPLE(open)
 ADD_EXAMPLE(savenpy)
 ADD_EXAMPLE(savetxt)
 ADD_EXAMPLE(print_array)
+ADD_EXAMPLE(print_array_brief)

example/io/example_print_array_brief.f90

@@ -0,0 +1,20 @@
+program example_io_print_array_brief
+
+    use stdlib_io, only: print_array
+    implicit none
+
+    real, dimension(123, 456) :: array
+
+    call random_number(array)
+
+    print "(a)", "=== print_array ==="
+    call print_array(array, delimiter=', ', brief=.true.)
+
+end program example_io_print_array_brief
+
+! === print_array ===
+!  5.44562101E-01,  5.97862303E-01,  1.64548337E-01, ...,  1.18231595E-01
+!  6.42154396E-01,  8.24955523E-01,  2.37900555E-01, ...,  6.27207816E-01
+!  6.64815307E-02,  8.11999142E-01,  2.75685191E-01, ...,  4.20989931E-01
+! ...
+!  8.61099184E-01,  6.91828251E-01,  2.91268706E-01, ...,  3.90086174E-01