* #65 - add sassOptions for docs

fix docs with error: 'options has an unknown property 'indentedSyntax'.'
which new sass-loader are writen in 'sassOptions';
This should also cause quick prototyping's sass setting, after executing '$vue serve'

* #65 - sassOptions fix for sass-loader

* #65 - fix sassOptions - lang:ru

* add comment for sassOptions version

* add comment for sassOptions

* add comment for sassOptions

* Update docs/guide/pre-processors.md
Co-Authored-By: Haoqun Jiang <haoqunjiang@gmail.com>

* Update pre-processors.md

* Update pre-processors.md