Readme: Add support for NOTE, TIP, WARNING, IMPORTANT, and CAUTION notations

[kzu]

Related Problem

No response

The Elevator Pitch

Highlighting important parts of a package documentation is crucial to creating a more engaging experience.

In GitHub, the following readme markup:

> [!NOTE]
> This is a note

> [!TIP]
> This is a tip

> [!WARNING]
> This is a warning

> [!IMPORTANT]
> This is important

> [!CAUTION]
> This is a caution

Renders as follows

This is how the gallery renders that today: https://www.nuget.org/packages/Observable/0.2.0#readme-body-tab

Source for the examples: https://github.com/kzu/Observable

Additional Context and Details

Bringing nuget.org more aligned with GitHub markdown support is a good thing for OSS authors since it allows us to keep a unified readme in both places, lowering maintenance costs and avoiding duplication just to satisfy nuget.org restrictions on formatting.

[JonDouglas]

Looks like this is possible w/ markdig today:

https://github.com/xoofx/markdig/blob/master/src/Markdig.Tests/Specs/AlertBlockSpecs.md

[erdembayar]

See https://learn.microsoft.com/en-us/nuget/reference/errors-and-warnings/nu1605 for Note and Tip ones.

[kzu]

I could give it a shot at sending a PR if it would help this ship sooner than later 🙏 . Just let me know and I can figure it out.

Thanks!

[erdembayar]

Sure, you're welcome to create a PR. Please start with just one instead of all. If the first one is accepted, then we can proceed with the others.

Happy coding! 🧑‍💻

[erdembayar]

Please note that sometimes we ask for a spec review before starting implementation if it is going to change current behavior (e.g. how customers perceive), or if it will introduce any breaking changes or security concerns (for example, rendering requiring a new package, URL, or network call). Something like this: NuGet/Home#13673

[kzu]

Oh boy is this going to be "interesting":

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <UseNuGetBuildExtensions>true</UseNuGetBuildExtensions>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>

I thought I was never going to see that legacy format ever again :(

[erdembayar]

Oh boy is this going to be "interesting":

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <UseNuGetBuildExtensions>true</UseNuGetBuildExtensions>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>

I thought I was never going to see that legacy format ever again :(

It shouldn't be hard to migrate, there're tools for doing that, recently some community members migrated some for us (#10000)

[kzu]

And, dev branch build fails due to #10166. 😿

Added this to the relevant .csproj.user for now:

    <TreatWarningsAsErrors>false</TreatWarningsAsErrors>

[kzu]

Quick Q @erdembayar: does the nuget.org use markdig rendering? (starting from ConvertsMarkdownToHtml)

[kzu]

Ok, with an update to Markdig and a one-liner .UseAlertBlocks(), the following inline data passes for the mentioned test:

[InlineData(
    """
    > [!NOTE]
    > This is a note
    """,
    """
    <div class="markdown-alert markdown-alert-note alert alert-primary" dir="auto">
    <p class="markdown-alert-title" dir="auto"><svg class="octicon octicon-info mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M0 8a8 8 0 1 1 16 0A8 8 0 0 1 0 8Zm8-6.5a6.5 6.5 0 1 0 0 13 6.5 6.5 0 0 0 0-13ZM6.5 7.75A.75.75 0 0 1 7.25 7h1a.75.75 0 0 1 .75.75v2.75h.25a.75.75 0 0 1 0 1.5h-2a.75.75 0 0 1 0-1.5h.25v-2h-.25a.75.75 0 0 1-.75-.75ZM8 6a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z"></path></svg>Note</p>
    <p dir="auto">This is a note</p>
    </div>
    """,
    false, true)]

That matches (almost exactly, except for alert alert-primary in the outer div) the html in github.com.

All that remains is where to put the styles.

[zivkan]

IMO this should be validated with the NuGet Client team to ensure that it'll be possible to support in Visual Studio. Markdown features that only work on nuget.org and not Visual Studio won't be good for the ecosystem.

cc @jgonz120