[docs] 오타 수정

[jaeyeonling]

내용을 읽으며 보이는 몇가지 오타가 있어 수정 해봤습니다.

정리를 너무 잘해두셔서 저 같은 초급 개발자에게 많은 도움이 됩니다.

감사합니다!

[codecov]

Codecov Report

Merging #67 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #67   +/-   ##
=========================================
  Coverage     97.58%   97.58%           
  Complexity      128      128           
=========================================
  Files            37       37           
  Lines           372      372           
  Branches          4        4           
=========================================
  Hits            363      363           
  Misses            7        7           
  Partials          2        2

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[coveralls]

Pull Request Test Coverage Report for Build 166

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.118%

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Totals
Change from base Build 165:	0.0%
Covered Lines:	365
Relevant Lines:	372

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💛 - Coveralls

[cheese10yun]

감사합니다. 오타가 거의 테러 수준이네요... 앞으로는 신경 쓰겠습니다.
PR 다시 한번 감사드립니다.