Update sample DB instructions

[gewarren]

The sample DB isn't available on the Microsoft Download Center, so remove that part from the intros.
(Hide whitespace changes.)

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Internal previews

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docs/visual-basic/programming-guide/language-features/linq/how-to-call-a-stored-procedure-by-using-linq.md	How to: Call a Stored Procedure by Using LINQ (Visual Basic)
docs/visual-basic/programming-guide/language-features/linq/how-to-count-sum-or-average-data-by-using-linq.md	How to: Count, Sum, or Average Data by Using LINQ (Visual Basic)
docs/visual-basic/programming-guide/language-features/linq/how-to-filter-query-results-by-using-linq.md	"How to: Filter Query Results by Using LINQ"
docs/visual-basic/programming-guide/language-features/linq/how-to-find-the-minimum-or-maximum-value-in-a-query-result.md	How to: Find the Minimum or Maximum Value in a Query Result by Using LINQ (Visual Basic)
docs/visual-basic/programming-guide/language-features/linq/how-to-modify-data-in-a-database-by-using-linq.md	docs/visual-basic/programming-guide/language-features/linq/how-to-modify-data-in-a-database-by-using-linq
docs/visual-basic/programming-guide/language-features/linq/how-to-query-a-database-by-using-linq.md	How to: Query a Database by Using LINQ (Visual Basic)
docs/visual-basic/programming-guide/language-features/linq/how-to-return-a-linq-query-result-as-a-specific-type.md	"How to: Return a LINQ Query Result as a Specific Type"
docs/visual-basic/programming-guide/language-features/linq/how-to-sort-query-results-by-using-linq.md	How to: Sort Query Results by Using LINQ (Visual Basic)