chore: minor spelling fix (#360)

Simply fixes a small spelling mistake in the polynomial regression tfjs example.

Author: charles-m-knox

polynomial-regression/index.js

@@ -155,7 +155,7 @@ function toNormalizedTensors(xyData, order) {
 //   epochs: How many epochs to train for.
 //   learningRate: Learning rate.
 //
-// Returns: An Array consiting of the following:
+// Returns: An Array consisting of the following:
 //   The trained keras Model instance.
 //   xPowerMeans: Arithmetic means of the powers of x, from order `1` to
 //      order `order`