Document deprecation of indentedSyntax option

[lorefnon]

Documentation Is:

• [x] Missing
• [ ] Needed
• [x] Confusing
• [ ] Not Sure?

Please Explain in Detail...

As of this commit, passing sassOptions: { indentedSyntax: true } does nothing and instead we must pass sassOptions: { syntax: "indented" } to use indented syntax.

This breaks configurations that were relying on previous config and this is not documented anywhere.

This is particularly an issue for users of vue-loader because the file extension based autodetection does not work for embedded <style lang="sass">...</style> tags.

Your Proposal for Changes

• Please add the breaking change in CHANGELOG
• Document the syntax option in README

If a contributor is abel to confirm that this change was intentional, I can send a PR for the above.