docs: Advise use of non-interactive commands

If a doc contains commands, they should be non-interactive where
possible to allow for the possibility of automating the testing of the
document in the CI.

Fixes #477.

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

Documentation-Requirements.md

@@ -28,6 +28,13 @@ All documents must:
 
   If you are adding a new document, ensure you add a link to it in the
   "closest" `README` above the directory where you created your document.
+- If the document needs to tell the user to manipulate files or commands, use a
+  [code block](#code-blocks) to specify the commands.
+
+  If at all possible, ensure that every command in the code blocks can be run
+  non-interactively. If this is possible, the document can be tested by the CI
+  which can then execute the commands specified to ensure the instructions are
+  correct. This avoids documents becoming out of date over time.
 
 # Linking advice