review: src/guide/scaling-up/testing.md (vuejs#160)

* proofread test.md to line 238

* docs: proofread test.md

* docs(testing.md): 应用程序 => 应用

* docs(testing.md): revise word order

Co-authored-by: wxsm <[email protected]>

* docs(testing.md): 其它 => 其他

Co-authored-by: wxsm <[email protected]>

* docs(testing.md): E2E => 端到端

Co-authored-by: wxsm <[email protected]>

* docs(testing.md): add lost expression

Co-authored-by: wxsm <[email protected]>

* Update src/guide/scaling-up/testing.md

Co-authored-by: wxsm <[email protected]>

Author: SkyeYoung