Update post_construct.md

[alexander-joinlane]

Seems to be an inaccuracy in the Post Construct Decorator description (implementation seems correct)

Description

• use() returned a string, no visible side-effect → updated to console.log()
• testMethod() was not discernibly different from use() → updated to "Used ..." and "Tested ..."
• use() was not invoked → updated to invoke so that the log output would make more sense

I did this via Github interface, so conventional commits didn't seem to be available

Related Issue

N/A

Motivation and Context

Clarity of use and intent.

How Has This Been Tested?

N/A

Types of changes

N/A

Checklist:

N/A