Fix "modifized" typo on modified_zscores docstring

Signed-off-by: Charlie Tonneslan <cst0520@gmail.com>

src/quantity/statistics.rs

@@ -106,7 +106,7 @@ pub fn standard_deviation<Q: UnsafeRawValue>(values: &[Q], mean: Q) -> Q {
     Q::unsafe_from_raw_value((sum / (values.len() as f64 - 1.0)).sqrt())
 }
 
-/// Compute modifized Z-scores for a given sample. A (unmodified) Z-score is defined by
+/// Compute modified Z-scores for a given sample. A (unmodified) Z-score is defined by
 /// `(x_i - x_mean)/x_stddev` whereas the modified Z-score is defined by `(x_i - x_median)/MAD`
 /// where MAD is the median absolute deviation.
 ///