Update lectures/geom_series.md

Co-authored-by: Matt McKay <mmcky@users.noreply.github.com>

lectures/geom_series.md

@@ -968,7 +968,7 @@ values = [0.3, 0.4]
 ```
 
 First, plot the time paths of $y_t$ using the same initial values but with $i$ 
-taking the values mentioned above.
+taking the values above.
 
 Next, plot the time paths of $y_t$ with the same initial values but let $g$ take
 the values abovementioned.