(AB-4196) Codify markdownlint

[michaeltlombardi]

PR Summary

Prior to this change, the repository had no markdownlint configuration. This change adds configuration based on the rules defined in the MicrosoftDocs/PowerShell-Docs project.

The root-folder .markdownlint.json file specifies the enforced syntax for Markdown files in this project.

The root-folder .markdownlint-cli2.yaml file governs the behavior of the linter overall. The settings included are minimal and do not effect the editing experience. This file may require iteration for advanced usage later.

In every About folder for reference content, this change adds a .markdownlint.json file. When editing Markdown in VS Code, the editor uses the closest configuration file to the edited document. That allows us to override and specify alternate rules on a per-folder basis.

In this change, the configuration files in the About folders:

• Extend the root configuration. Any settings not specified in these configurations is inherited from the configuration at the project root.
• Overrides the line-length rule, setting the maximum line length for code blocks to 74 characters and for other text to 79 characters.This is to accomodate the PowerShell Help System's line length requirements.

In the rules folder for PSScriptAnalyzer's conceptual content, this change adds a .markdownlint.json file which ignores the markdownlint rule no-emphasis-as-heading. PSSA rules indicate their severity level by a single line of emphasized text.

This change is related to AB#4196 and AB#4197.

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[opbld33]

Docs Build status updates of commit 610b32f:

✅ Validation status: passed

File	Status	Preview URL	Details
.markdownlint.json	✅Succeeded
.markdownlint-cli2.yaml	✅Succeeded
reference/docs-conceptual/PSScriptAnalyzer/Rules/.markdownlint.json	✅Succeeded
reference/ps-modules/Microsoft.PowerShell.Crescendo/About/.markdownlint.json	✅Succeeded
reference/ps-modules/PlatyPS/About/.markdownlint.json	✅Succeeded

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

• Try searching the docs.microsoft.com contributor guides
• Post your question in the Docs support channel