Add Azure Pipelines badge to readme (#22828)

Author: zooba

README.md

@@ -61,6 +61,14 @@
     </a>
   </td>
 </tr>
+<tr>
+  <td></td>
+  <td>
+    <a href="https://dev.azure.com/pandas-dev/pandas/_build/latest?definitionId=1&branch=master">
+      <img src="https://dev.azure.com/pandas-dev/pandas/_apis/build/status/pandas-dev.pandas?branch=master" alt="Azure Pipelines build status" />
+    </a>
+  </td>
+</tr>
 <tr>
   <td>Coverage</td>
   <td>