doc: rephrase documentation for child_process.execSync()

[aashil]

The line at the end describing about the error thrown can be worded better.

If the process times out, or has a non-zero exit code, this method will throw. The Error object will contain the entire result from child_process.spawnSync()

Should be something like:

If the process times out, or has a non-zero exit code, this method will throw an Error object which will contain the entire result from child_process.spawnSync()

https://nodejs.org/api/child_process.html#child_process_child_process_execsync_command_options

[refack adding]

node/doc/api/child_process.md

Lines 687 to 689 in 467385a

	If the process times out, or has a non-zero exit code, this method ***will***
	throw. The [`Error`][] object will contain the entire result from
	[`child_process.spawnSync()`][]

[refack]

I'd tweak the last part as well:

...
throw an [`Error`][] that will include the full result of the underlying
[`spawnSync()`][].
...
<!-- link definition in the footer -->
[`spawnSync()`]: #child_process_child_process_execsync_command_options

[refack]

/cc @nodejs/documentation

[gibfahn]

Both suggested changes sound reasonable.

[ayazhafiz]

I'd like to pick this up!

[refack]

@ayazhafiz yours. (marked issue as in progress)
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