chore: fix typo in mapSlices example (#3392)

Trivial change, merging myself

Author: gwhitney

src/expression/embeddedDocs/function/matrix/mapSlices.js

@@ -8,7 +8,7 @@ export const mapSlicesDocs = {
   examples: [
     'A = [[1, 2], [3, 4]]',
     'mapSlices(A, 1, sum)', // returns [4, 6]
-    'mapSlices(A, 2, product)' // returns [2, 12]
+    'mapSlices(A, 2, prod)' // returns [2, 12]
   ],
   seealso: ['map', 'forEach']
 }