Use 'std::tuple' in examples instead of a C array

This should be clearer since C arrays *are* ranges; it's just that
the standard specifically excludes array types from being
expansion-iterable; it should be a bit more obvious that this is
supposed to be destructuring if we use 'std::tuple' as an example.

Author: Sirraide

clang/include/clang/AST/DeclTemplate.h

@@ -3375,7 +3375,7 @@ class TemplateParamObjectDecl : public ValueDecl,
 ///
 /// For example, if the user writes the following expansion statement:
 /// \verbatim
-///   int a[3]{1, 2, 3};
+///   std::tuple<int, int, int> a{1, 2, 3};
 ///   template for (auto x : a) {
 ///     // ...
 ///   }

clang/include/clang/AST/StmtCXX.h

@@ -897,7 +897,7 @@ class CXXDestructuringExpansionStmt : public CXXExpansionStmt {
 /// following expansion statement
 ///
 /// \verbatim
-///   int a[3]{1, 2, 3};
+///   std::tuple<int, int, int> a{1, 2, 3};
 ///   template for (auto x : a) {
 ///     // ...
 ///   }