docs: Remove bang from code block

Remove the `!` from the `echo` in the code example in the doc
requirements doc.

The current code is in fact invalid as the shell will try to interpret
the exclamation mark as it is a reserved word. Rather than escaping it
in the example, just remove it.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

Documentation-Requirements.md

@@ -72,7 +72,7 @@ utility.
       ```bash
       $ echo "Hi - I am some bash code"
       $ sudo docker run -ti busybox true
-      $ [ $? -eq 0 ] && echo "success!"
+      $ [ $? -eq 0 ] && echo "success"
       ```
 
   ```