Doc: Fix double underscore rsync attribute documentation
Adds button styles for simple pagination
Adds previous and next buttons to getting started guide
Replaced tabs with spaces, should now be consistent with the rest of the file
Consistent usage of spaces in the _base.less file

I noticed that there wasn't a consistent usage of tabs or spaces at all in the file, so now there is. Sorry for the extra commit, file looks better now.
Merge pull request #5031 from databus23/patch-4

Doc: Fix double underscore rsync attribute documentation
Merge pull request #5034 from HerrBertling/add-pagination-to-getting-started-guide

Add pagination to getting started guide