Modify Hello World in Fortran (#5120)

Improve Hello World Fortran code snippet

Author: pascalecu

archive/f/fortran/hello-world.f95

@@ -1,3 +1,4 @@
-PROGRAM HELLOWORLD
-  PRINT *, 'Hello, World!'
-END
+program helloworld
+   implicit none
+   print '(A)', 'Hello, World!'
+end program helloworld