chore: update sponsors [ci skip] (#11866)

BACKERS.md

@@ -58,7 +58,7 @@ Funds donated via Patreon go directly to support Evan You's full-time work on Vu
         </a>
       </td>
       <td align="center" valign="middle">
-        <a href="https://ionicframework.com/" target="_blank">
+        <a href="https://ionicframework.com/vue?utm_source=partner&utm_medium=referral&utm_campaign=vuesponsorship&utm_content=vuedocs" target="_blank">
           <img width="222px" src="https://raw.githubusercontent.com/vuejs/vuejs.org/master/themes/vue/source/images/ionic.png">
         </a>
       </td>

README.md

@@ -68,7 +68,7 @@ Funds donated via Patreon go directly to support Evan You's full-time work on Vu
         </a>
       </td>
       <td align="center" valign="middle">
-        <a href="https://ionicframework.com/" target="_blank">
+        <a href="https://ionicframework.com/vue?utm_source=partner&utm_medium=referral&utm_campaign=vuesponsorship&utm_content=vuedocs" target="_blank">
           <img width="222px" src="https://raw.githubusercontent.com/vuejs/vuejs.org/master/themes/vue/source/images/ionic.png">
         </a>
       </td>