docs(intro): make some changes for egg-and-koa

[SunShinewyf]

Checklist

• npm test passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

Description of change

修改了一些文档中语法明显错误的地方

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@d752b3b). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1739   +/-   ##
=========================================
  Coverage          ?   99.58%           
=========================================
  Files             ?       29           
  Lines             ?      717           
  Branches          ?        0           
=========================================
  Hits              ?      714           
  Misses            ?        3           
  Partials          ?        0

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d752b3b...133bf3c. Read the comment docs.

[atian25]

这个等 #1713 合并后再重新改改，那边有修改了对应的文件

[SunShinewyf]

好的

[dead-horse]

可以 rebase 了

[atian25]

@SunShinewyf 可以重新在新的基础上改了.