bugfix: a typo in CONTRIBUTTING.md

[zhuorantan]

Ⅰ. Describe what this PR did

Fix a typo in CONTRIBUTING.md

Ⅱ. Does this pull request fix one issue?

No

Ⅲ. Describe how you did it

Change "you" to "your"

Ⅳ. Describe how to verify it

English grammar

Ⅴ. Special notes for reviews

Team 10

[CLAassistant]

All committers have signed the CLA.

[pouchrobot]

We found this is your first time to contribute to Pouch, @JeromeTan1997
👏 We really appreciate it.
Just remind that you have read the contribution guide: https://github.com/alibaba/pouch/blob/master/CONTRIBUTING.md
If you didn't, you should do that first. If done, welcome again and please enjoy hacking! 🍻

[fuweid]

@JeromeTan1997 Thanks for your contribution. Could you please use the following statement to repush your change?

git commit -s --amend
git push -f origin typo

Thanks

[zhuorantan]

@fuweid Done😀

[codecov-io]

Codecov Report

Merging #1775 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1775      +/-   ##
==========================================
+ Coverage   56.32%   56.36%   +0.03%     
==========================================
  Files         200      200              
  Lines       15657    15657              
==========================================
+ Hits         8819     8825       +6     
+ Misses       5742     5739       -3     
+ Partials     1096     1093       -3

Flag	Coverage Δ
#critest	33.55% <ø> (+0.07%)	⬆️
#integrationtest	37.65% <ø> (-0.04%)	⬇️
#unittest	20.33% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
ctrd/image.go	78.71% <0%> (-0.5%)	⬇️
daemon/mgr/container.go	53.3% <0%> (ø)	⬆️
cri/v1alpha2/cri.go	66.13% <0%> (+0.17%)	⬆️
ctrd/container.go	50.17% <0%> (+1.37%)	⬆️
apis/server/utils.go	66.66% <0%> (+4.76%)	⬆️

[fuweid]

LGTM