Fix missing docs example for "Mnemonics which contain a period"
@@ -339,7 +339,7 @@ Mnemonics which contain a period
As with other LAS file parsers, lasio does not parse mnemonics which contain
a period - instead, anything after the period will be parsed as the unit:
-.. code-block::
+.. code-block:: none
SP.COND .US/M : EC at 25 deg C
