Fixed grammatical issues

[geekygirl8]

PR Checklist

• [x] The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• [ ] If there is an issue related to this PR, point it out here.

What is the current state of the documentation article?

The grammar of the CODE_OF_CONDUCT.md file not correct.

What is the new state of the documentation article?

Made required changes to enhance readability and ensured grammar is correct.

Fixes/Implements/Closes #[Issue Number].

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[geekygirl8]

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