projf: change code to code-block

Signed-off-by: Kamil Rakoczy <krakoczy@antmicro.com>

projf-makefiles/hello/hello-arty/A/README.rst

@@ -4,13 +4,13 @@ Part 1 Design A
 This design allows you to turn the first led on the arty board on and off by toggling switch 0. 
 To build this design run the following command in the main symbiflow directory:
 
-.. code:: bash
+.. code-block:: bash
    :name: hello-arty-A
 
    TARGET="arty_35" make -C projf-makefiles/hello/hello-arty/A
 
 You can then download the bitstream by running:
 
-.. code:: bash
+.. code-block:: bash
 
    TARGET="arty_35" make download -C projf-makefiles/hello/hello-arty/A