Documentation: Start special topic page on aliasing.
diff --git a/doc/snippets/TopicAliasing_block.cpp b/doc/snippets/TopicAliasing_block.cpp
new file mode 100644
index 0000000..9e897d0
--- /dev/null
+++ b/doc/snippets/TopicAliasing_block.cpp
@@ -0,0 +1,5 @@
+Matrix3i mat; 
+mat << 1, 2, 3,   4, 5, 6,   7, 8, 9;
+cout << "Here is the matrix mat:\n" << mat << endl;
+mat.bottomRightCorner(2,2) = mat.topLeftCorner(2,2);
+cout << "After the assignment, mat = \n" << mat << endl;