org: fix example generation

* doc/org/autfilt.org, doc/org/dstar2tgba.org: Here.  Many examples
failed because the code generating the input was not run.

doc/org/autfilt.org

@@ -27,7 +27,7 @@ same stream, =autfilt= will process them in batch.
 The output format can be controlled using [[file:oaut.org][the common output options]]
 (like =--spin=, =--lbtt=, =--dot=, =--hoaf=...).
 
-#+BEGIN_SRC sh :results verbatim :exports code
+#+BEGIN_SRC sh :results silent :exports code
 cat >example.hoa <<EOF
 HOA: v1
 States: 1
@@ -288,7 +288,7 @@ autfilt --help | sed -n '/Transformations:/,/^$/p' | sed '1d;$d'
 
 Here is an automaton with transition-based acceptance:
 
-#+BEGIN_SRC sh :result verbatim :export code
+#+BEGIN_SRC sh :result silent :export code
 cat >aut-ex1.hoa<<EOF
 HOA: v1
 States: 3

doc/org/dstar2tgba.org

@@ -24,7 +24,7 @@ The following command instructs =ltl2dstar= to:
 Additionally we use =ltlfilt= to convert our formula to the
 prefix format used by =ltl2dstar=.
 
-#+BEGIN_SRC sh :results verbatim :exports node
+#+BEGIN_SRC sh :results silent :exports code
 ltlfilt -f 'Fa & GFb' -l | ltl2dstar --ltl2nba=spin:ltl2tgba@-sD - fagfb
 #+END_SRC