Add support to stop TiDB gracefully (#2810)

* graceful stop tidb

* address comment

Co-authored-by: DanielZhangQD <36026334+DanielZhangQD@users.noreply.github.com>

docs/api-references/docs.md

@@ -3296,6 +3296,40 @@ tidb-operator built envs.
 supports additional volume mounts for sidecar containers.</p>
 </td>
 </tr>
+<tr>
+<td>
+<code>terminationGracePeriodSeconds</code></br>
+<em>
+int64
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Optional duration in seconds the pod needs to terminate gracefully. May be decreased in delete request.
+Value must be non-negative integer. The value zero indicates delete immediately.
+If this value is nil, the default grace period will be used instead.
+The grace period is the duration in seconds after the processes running in the pod are sent
+a termination signal and the time when the processes are forcibly halted with a kill signal.
+Set this value longer than the expected cleanup time for your process.
+Defaults to 30 seconds.</p>
+</td>
+</tr>
+<tr>
+<td>
+<code>lifecycle</code></br>
+<em>
+<a href="https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.13/#lifecycle-v1-core">
+Kubernetes core/v1.Lifecycle
+</a>
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Lifecycle describes actions that the management system should take in response to container lifecycle
+events. For the PostStart and PreStop lifecycle handlers, management of the container blocks
+until the action is complete, unless the container process fails, in which case the handler is aborted.</p>
+</td>
+</tr>
 </tbody>
 </table>
 <h3 id="configmapref">ConfigMapRef</h3>