NuGet: Use license expression

[vanillajonathan]

Use a SPDX license expression to specify MIT instead of pointing to the LICENSE file.

Reference: https://docs.microsoft.com/en-us/nuget/reference/nuspec#license

[julien-deramond]

Thanks for the PR. Got a few questions here.

Atm when we go to https://www.nuget.org/packages/bootstrap/ we have a "License info" link.

I suppose that with this PR we would have we would have the equivalent of what we can see in https://www.nuget.org/packages/Newtonsoft.Json/13.0.2-beta1 with a "MIT license". If we click on this MIT link we can see that some information are missing.

Wouldn't be the same with your proposal or does it use automatically IDK <authors> and/or <copyright> info from the *.nuspec files? How do we add for example what we currently have in our license? for example:

Copyright (c) 2011-2021 Twitter, Inc.
Copyright (c) 2011-2021 The Bootstrap Authors

Seems interesting to use the SPDX format in order to see what kind of license is used directly in the NuGet Gallery (this value is maybe used as well by 3rd party tools as well) but I'd say it's important that we can keep all existing info.

@XhmikosR Any thoughts? Have things like that been already tried out?

[vanillajonathan]

I don't know. But this is the way other packages do it too, including Microsoft:
Example https://www.nuget.org/packages/System.Net.Http.Json and https://www.nuget.org/packages/Microsoft.EntityFrameworkCore/

[XhmikosR]

/CC @supergibbs who is handling the NuGet packages

[supergibbs]

Looks good to me, except the license file would change. The copyright info is displayed on nuget.org which is just the dates right now. If you want to show:

Copyright (c) 2011-2022 Twitter, Inc.
Copyright (c) 2011-2022 The Bootstrap Authors

we can update the .nuspec files accordingly

[mdo]

We should simplify to The Bootstrap Authors for everywhere IMO—we can drop the Twitter mention after ~10 years of them having nothing to do with it lol.

[supergibbs]

I can't officially approve, but looks good to me

[supergibbs]

@vanillajonathan Actually noticed something, .nuspec files should remove <file src="LICENSE.txt" target="" />

[vanillajonathan]

@supergibbs Done!

[XhmikosR]

Not sure if we need to backport this to v4-dev.