Add a -MaxAboutWidth parameter to New-ExternalHelp.

[jazzdelightsme]

fixes #298

[msftclas]

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[jazzdelightsme]

I noticed that New-ExternalHelp does not actually wrap everything to the specified width, but I don't know if that's By Design or what.

[vors]

Yeah, this maxLineWidth parameter is actually not used at all. https://github.com/PowerShell/platyPS/blob/master/src/Markdown.MAML/Renderer/Markdownv2Renderer.cs#L44

[vors]

The markdown renderer should not be actually used at all when we producing the txt files for about topics.

[jazzdelightsme]

The markdown renderer should not be actually used at all when we producing the txt files for about topics.

You are correct. But I'm not passing $MaxAboutWidth to the markdown renderer... see line 861--I'm passing it to the TextRenderer constructor, and I have verified experimentally that it is used.

Steps:

1. New-MarkdownAboutHelp -OutputFolder . -AboutName testThing
2. Open .\about_testThing.md in an editor and add content to a bunch of lines, extending them out to 125 characters.
3. New-ExternalHelp -MaxAboutWidth 90 -OutputPath . -Path .\about_testThing.md
4. Open .\about_testThing.help.txt in an editor, and verify that certain lines got wrapped to be no longer than 90 characters.

This time I noticed that it's the "code" sections (marked by backticks) that do not get wrapped, which I think is reasonable.

[vors]

Oh I see. Cool, let's update the help for the platyPS itself and add this to the "Unreleased" section in the Changelog.md and it will be good to go.