Add missing snippet files.
diff --git a/doc/snippets/MatrixBase_selfadjointView.cpp b/doc/snippets/MatrixBase_selfadjointView.cpp
new file mode 100644
index 0000000..4bd3c7e
--- /dev/null
+++ b/doc/snippets/MatrixBase_selfadjointView.cpp
@@ -0,0 +1,6 @@
+Matrix3i m = Matrix3i::Random();
+cout << "Here is the matrix m:" << endl << m << endl;
+cout << "Here is the symmetric matrix extracted from the upper part of m:" << endl
+ << Matrix3i(m.selfadjointView<Upper>()) << endl;
+cout << "Here is the symmetric matrix extracted from the lower part of m:" << endl
+ << Matrix3i(m.selfadjointView<Lower>()) << endl;