docs: correct README following markdown rules

[JeffGuKang]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Add some line break in README.

Approach

TODOs before merging

• Add tests
• Add changes to documentation (guides, repository pages, in-code descriptions)
• Add security check
• Add new Parse Error codes to Parse JS SDK
• A changelog entry is created automatically using the pull request title (do not manually add a changelog entry)

[parse-github-assistant]

Thanks for opening this pull request!

• ❌ Please link an issue that describes the reason for this pull request, otherwise your pull request will be closed. Make sure to write it as Related issue: #123 in the PR description, so I can recognize it.

[codecov]

Codecov Report

Merging #8024 (518f649) into alpha (c6dcad8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            alpha    #8024   +/-   ##
=======================================
  Coverage   94.13%   94.13%           
=======================================
  Files         182      182           
  Lines       13634    13634           
=======================================
  Hits        12834    12834           
  Misses        800      800           

Impacted Files	Coverage Δ
src/RestWrite.js	94.41% <0.00%> (ø)

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[parseplatformorg]

🎉 This change has been released in version 5.3.0-alpha.15

[parseplatformorg]

🎉 This change has been released in version 5.3.0-beta.1

[parseplatformorg]

🎉 This change has been released in version 5.3.0