Modify helloworld demo of README

[xg1907]

No description provided.

[CLAassistant]

All committers have signed the CLA.

[codecov-io]

Codecov Report

Merging #5 into master will increase coverage by 0.13%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master      #5      +/-   ##
===========================================
+ Coverage     46.37%   46.5%   +0.13%     
- Complexity      544     545       +1     
===========================================
  Files           105     105              
  Lines          3651    3651              
  Branches        517     517              
===========================================
+ Hits           1693    1698       +5     
+ Misses         1753    1749       -4     
+ Partials        205     204       -1

Impacted Files	Coverage Δ	Complexity Δ
...a/com/alibaba/csp/sentinel/node/StatisticNode.java	64.91% <0%> (+1.75%)	16% <0%> (ø)	⬇️
...ibaba/csp/sentinel/eagleeye/EagleEyeLogDaemon.java	30.3% <0%> (+6.06%)	6% <0%> (+1%)	⬆️

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[sczyh30]

Thanks for your PR!