Merge pull request #531 from Szer/patch-1

Create snipper6704.fs

Author: cartermp

snippets/fsharp/lang-ref-2/snippet6704.fs

@@ -0,0 +1,15 @@
+```fsharp
+[<Struct>]
+type Foo =
+  val mutable bar: string
+  member self.ChangeBar bar = self.bar <- bar
+  new (bar) = {bar = bar}
+
+let foo = Foo "1"
+foo.ChangeBar "2" //make implicit copy of Foo, changes the copy, discards the copy, foo remains unchanged
+printfn "%s" foo.bar //prints 1
+
+let mutable foo' = Foo "1"
+foo'.ChangeBar "2" //changes foo'
+printfn "%s" foo'.bar //prints 2
+```