Docs: fix code-example blocks in varLib.

Lib/fontTools/varLib/__init__.py

@@ -10,10 +10,14 @@ ttf-interpolatable files for the masters and build a variable-font from
 them.  Such ttf-interpolatable and designspace files can be generated from
 a Glyphs source, eg., using noto-source as an example:
 
+    .. code-block:: sh
+
 	$ fontmake -o ttf-interpolatable -g NotoSansArabic-MM.glyphs
 
 Then you can make a variable-font this way:
 
+    .. code-block:: sh
+
 	$ fonttools varLib master_ufo/NotoSansArabic.designspace
 
 API *will* change in near future.

Lib/fontTools/varLib/mutator.py

@@ -1,7 +1,9 @@
 """
 Instantiate a variation font.  Run, eg:
 
-$ fonttools varLib.mutator ./NotoSansArabic-VF.ttf wght=140 wdth=85
+.. code-block:: sh
+
+    $ fonttools varLib.mutator ./NotoSansArabic-VF.ttf wght=140 wdth=85
 """
 
 from fontTools.misc.fixedTools import floatToFixedToFloat, floatToFixed
@@ -162,6 +164,8 @@ def instantiateVariableFont(varfont, location, inplace=False, overlap=True):
     defining the desired location along the variable font's axes.
     The location values must be specified as user-space coordinates, e.g.:
 
+    .. code-block::
+
         {'wght': 400, 'wdth': 100}
 
     By default, a new TTFont object is returned. If ``inplace`` is True, the