Add comprehensive guidelines for custom instruction files, localizati…

[SamErde]

…on, markdown standards, PowerShell Pester testing, and cmdlet development best practices

• Introduced a new instruction file for creating high-quality custom instruction files for GitHub Copilot.
• Added guidelines for localizing markdown documents, including directory structure and disclaimers.
• Established documentation and content creation standards for markdown files.
• Provided PowerShell Pester v5 testing best practices, including test structure and assertions.
• Created a detailed guide for PowerShell cmdlet and scripting best practices based on Microsoft guidelines.
• Developed guidelines for creating effective prompt files for GitHub Copilot, covering structure, input handling, and quality assurance.

[Copilot]

Pull Request Overview

This PR introduces a comprehensive set of guidelines for GitHub Copilot customization, covering instruction files, localization, markdown standards, PowerShell development, Pester testing, GitHub Actions CI/CD, accessibility, and prompts. The additions establish project-wide conventions to improve code quality, consistency, and maintainability.

• Adds seven new instruction files providing detailed guidance for various development domains
• Updates existing Copilot instructions to be more general-purpose
• Removes repository-specific configuration from Codacy instructions

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/instructions/prompt.instructions.md	Establishes guidelines for creating effective prompt files for GitHub Copilot
.github/instructions/powershell.instructions.md	Defines PowerShell cmdlet development best practices based on Microsoft guidelines
.github/instructions/powershell-pester-5.instructions.md	Provides comprehensive Pester v5 testing standards for PowerShell
.github/instructions/markdown.instructions.md	Sets documentation and content creation standards for markdown files
.github/instructions/localization.instructions.md	Outlines procedures for localizing markdown documents
.github/instructions/instructions.instructions.md	Meta-guidelines for creating high-quality custom instruction files
.github/instructions/github-actions-ci-cd-best-practices.instructions.md	Comprehensive CI/CD pipeline best practices for GitHub Actions
.github/instructions/codacy.instructions.md	Removes repository-specific configuration to make it more general
.github/instructions/a11y.instructions.md	Comprehensive accessibility guidelines for code generation
.github/copilot-instructions.md	Generalizes commit message template to be project-agnostic

[Copilot]

Line 12 (previously line 13) has incorrect indentation. The organization property should align with the provider property above it, using a consistent indentation pattern of either 2 or 4 spaces. Currently appears to have misaligned spacing.