Bad reference in one description of Chapter 8

[dwaps]

Hi,

In the index.adoc (nodebook/chapter-08/), the flag --option in the sentence :
<1> Omission de la valeur de --option et tentative d'affectation de valeur à l'option booléenne --fast
does not exist in the related example.

The correct flag is --country.

Link to your document: https://github.com/oncletom/nodebook/blob/524edca4a97d937f23bb59db16a4d3ae21fa9cb8/chapter-08/index.adoc

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