[docs] knights of Pi

[Martin Feuchtwanger]

Similarly,

	print  'The value of PI is approximately {}.'.format(math.pi)

should be

	print  'The value of PI is approximately {0}.'.format(math.pi)

-- 
Martin Feuchtwanger, PhD   martinf at underhill.ca   604-732-3384 x 206
Underhill Geomatics Ltd.   www.underhill.ca
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