Update CLU example; it will now make an executable file.

src/hello/hello.clu

@@ -1,5 +1,18 @@
 % Hello world example for CLU.
 
+% To make an executable:
+% 1. Type :CWD HELLO to change the working directory.
+% 2. Type :CLU HELLO to compile this file.
+% 3. Type :CLU;CLUSYS to start the CLU runtime system.
+% 4. At the runtime : prompt, type fload("hello")
+% 5. Then type gc_pure_dump("hello; ts hello")
+
 hello = proc()
       file$puts (file$tyo(), "Hello CLU-less world!\n")
-end
+end hello
+
+% The CLU runtime calls start_up.  This procedure overrides the default.
+start_up = proc()
+      hello()
+      quit_()
+end start_up