Adjusted incorrect underline.

docs/source/input.rst

@@ -109,7 +109,7 @@ General commands
 Allows you to write blocks of Python code between ``#python`` and ``#end_python`` in the input file. The code is executed when the input file is read by gprMax. For further details see the :ref:`Python section <python-scripting>`.
 
 #include:
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+---------
 
 Allows you to input include commands from a file. It will insert the commands from the specified file at the location where the ``#include`` commands is placed. The syntax of the command is: