fixed a49ce7d4 from https://gitee.com/ge-yafang/docs/pulls/5669

update zh-cn/application-dev/windowmanager/screenshot-overview.md.
Signed-off-by: N@ge-yafang <geyafang@huawei.com>

zh-cn/application-dev/windowmanager/screenshot-overview.md

-# 屏幕截图开发指导
+# 屏幕截图开发概述
 
 提供指定显示设备下特定参数的屏幕截图能力。