Mention associativity of exponentiation operator

[ghost]

It's worth to mention that the exponentiation operator (**) is right associative, 2 ** 3 ** 4 is equal to 2 ** (3 ** 4).

[swaroopch]

@luz30 I went through the text again, and I feel that while this is accurate, it may not add value to a beginner's text. It may too much information at this stage of someone's learning.