[SPARK-18188][DOC][FOLLOW-UP] Add spark.broadcast.checksum to configuration

## What changes were proposed in this pull request?

This pr add `spark.broadcast.checksum` to configuration.

## How was this patch tested?
manually tested

Author: liuxian <[email protected]>

Closes #21825 from 10110346/checksum_config.

Author: 10110346

docs/configuration.md

@@ -1217,6 +1217,15 @@ Apart from these, the following properties are also available, and may be useful
     if it is too small, <code>BlockManager</code> might take a performance hit.
   </td>
 </tr>
+<tr>
+  <td><code>spark.broadcast.checksum</code></td>
+  <td>true</td>
+  <td>
+    Whether to enable checksum for broadcast. If enabled, broadcasts will include a checksum, which can
+    help detect corrupted blocks, at the cost of computing and sending a little more data. It's possible
+    to disable it if the network has other mechanisms to guarantee data won't be corrupted during broadcast.
+  </td>
+</tr>
 <tr>
   <td><code>spark.executor.cores</code></td>
   <td>