Update index.tsx

[wanliyunyan]

First of all, thank you for your contribution! :-)

Please makes sure that these checkboxes are checked before submitting your PR, thank you!

• Make sure that you propose PR to right branch: bugfix for master, feature for latest active branch feature-x.x.
• Make sure that you follow antd's code convention.
• Run npm run lint and fix those errors before submitting in order to keep consistent code style.
• Rebase before creating a PR to keep commit history clear.
• Add some descriptions and refer relative issues for you PR.

Extra checklist:

if isBugFix :

• Make sure that you add at least one unit test for the bug which you had fixed.

elif isNewFeature :

• Update API docs for the component.
• Update/Add demo to demonstrate new feature.
• Update TypeScript definition for the component.
• Add unit tests for the feature.

[nikogu]

ci broke: https://travis-ci.org/ant-design/ant-design/jobs/333177882#L5352

[wanliyunyan]

@nikogu I do not understand how to modify, can you help me?

[nikogu]

@wanliyunyan please rebase master, the ci broken was be fixed already.

[codecov]

Codecov Report

Merging #9126 into master will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9126      +/-   ##
==========================================
+ Coverage   85.26%   85.32%   +0.06%     
==========================================
  Files         195      195              
  Lines        4677     4683       +6     
  Branches     1379     1380       +1     
==========================================
+ Hits         3988     3996       +8     
+ Misses        689      687       -2

Impacted Files	Coverage Δ
components/steps/index.tsx	100% <ø> (ø)	⬆️
components/date-picker/RangePicker.tsx	96.63% <0%> (+1.94%)	⬆️

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[afc163]

close #9119