Finish doc page on aliasing.
diff --git a/doc/snippets/TopicAliasing_mult3.cpp b/doc/snippets/TopicAliasing_mult3.cpp
new file mode 100644
index 0000000..1d12a6c
--- /dev/null
+++ b/doc/snippets/TopicAliasing_mult3.cpp
@@ -0,0 +1,4 @@
+MatrixXf matA(2,2); 
+matA << 2, 0,  0, 2;
+matA.noalias() = matA * matA;
+cout << matA;