Docs: add typescript usage (#484)

Closes #313

Author: JPeer264

README.md

@@ -106,6 +106,33 @@ export default {
 }
 ```
 
+or in TypeScript
+
+```ts
+// CommitChart.ts
+import { Bar } from 'vue-chartjs';
+import { Component } from 'vue-property-decorator';
+
+@Component({
+    extends: Bar, // this is important to add the functionality to your component
+})
+export default class CommitChart extends Vue<Bar> {
+  mounted () {
+    // Overwriting base render method with actual data.
+    this.renderChart({
+      labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
+      datasets: [
+        {
+          label: 'GitHub Commits',
+          backgroundColor: '#f87979',
+          data: [40, 20, 12, 39, 10, 40, 39, 80, 40, 20, 12, 11]
+        }
+      ]
+    })
+  }
+}
+```
+
 Then simply import and use your own extended component and use it like a normal vue component
 
 ```javascript