DOC Fix pinball loss fomula in linear_model.rst
A minus sign got lost there.
@@ -1512,7 +1512,7 @@ see also :class:`~sklearn.metrics.mean_pinball_loss`,
\begin{cases}
q t, & t > 0, \\
0, & t = 0, \\
- (1-q) t, & t < 0
+ (q-1) t, & t < 0
\end{cases}
and the L1 penalty controlled by parameter ``alpha``, similar to
