Added user-friendly installation instructions

[admercs]

PR Summary

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation
• This PR is ready to merge and is not Work in Progress.
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[Copilot]

Pull Request Overview

This PR adds inline PowerShell commands to the README.md file to provide users with a quick installation method for PSScriptAnalyzer directly from the documentation, complementing the existing link to the detailed installation guide.

• Added inline PowerShell code snippet for installing PSScriptAnalyzer from PowerShell Gallery
• Provided command to set PSGallery as a trusted repository before installation

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[Copilot]

The -Scope parameter should be specified for Install-Module to clarify where the module will be installed. Without it, PowerShell will attempt to install to AllUsers scope which requires elevated permissions, potentially causing the command to fail for non-admin users.

Consider updating to:

Install-Module -Name PSScriptAnalyzer -Scope CurrentUser

This allows users to install the module without requiring administrator privileges.

Suggested change

	Install-Module -Name PSScriptAnalyzer
	Install-Module -Name PSScriptAnalyzer -Scope CurrentUser