doc: fix grammar and punctuation in child_process.md

[Rawal27]

Summary

Improve the grammar, punctuation, and clarity of several passages in the child_process documentation.

Changes

• Fix grammatical errors and punctuation issues.
• Improve awkward or ambiguous wording.
• Clarify conditional phrasing such as if any, else null.
• Preserve the existing technical meaning and documentation structure.

Documentation-only changes; no code changes or tests are required.

[aduh95]

Please stop opening PRs faster they can be reviewed. If you do not stop, you will get blocked from the organisation.

[Rawal27]

@aduh95 Can you clarify this? I mean, these are genuine doc-level changes that I have proposed. Also, a contributor can contribute to as many as 30 pull requests at a time. Closing them without reason seems unfair to me.

[Rawal27]

[jasnell]

@Rawal27 ... You are missing the point. 30 is a limit, not a goal. It's not an invitation to open 30 PRs as quickly as possible.

You've been asked to slow down and instead of doing so, you've just simply continued to open new PRs in addition to responding with this same screenshot and response in all of the closed PRs.