Incorrect interpretation of parameter

The interpretation of the IMD parameter in the [non-spatial regression](https://github.com/darribas/spa_notes/blob/master/sp_eco.Rmd#non-spatial-regression-a-refresh) section is incorrect. Where it reads:

> a unit increase in the degree of deprivation is associated with a 0.2% decrease in the price of a house

should read:

> a unit increase in the degree of deprivation is associated with a 25% decrease in the price of a house

This comes from the fact it is a log-linear functional form that can be interpreted, following Gelman & Hill (2006), as:

```tex
\beta = 0.2456446 \rightarrow exp(\beta) = 1.28
```

which implies a 28% increase in the non-log price variable we have as dependent.