chore: refactor getters code in example counter-hot (#1801)

Rewrite `recentHistory` getter using negative index for`start` argument of `Array.prototype.slice`.
Ref: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice

examples/counter-hot/store/getters.js

@@ -1,11 +1,7 @@
 export const count = state => state.count
 
-const limit = 5
-
 export const recentHistory = state => {
-  const end = state.history.length
-  const begin = end - limit < 0 ? 0 : end - limit
   return state.history
-    .slice(begin, end)
+    .slice(-5)
     .join(', ')
 }