Documentation: fill the placeholders, add a custom CSS file,

add a reference to the tutorial in the main page.

doc/examples/Tutorial_simple_example_dynamic_size.cpp

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+#include <Eigen/Core>
+
+// import most common Eigen's types 
+USING_PART_OF_NAMESPACE_EIGEN
+
+int main(int argc, char *argv[])
+{
+  for (int size=1; size<=4; ++size)
+  {
+    MatrixXi m(size,size+1);            // creates a size x (size+1) matrix of int
+    for (int j=0; j<m.cols(); ++j)      // loop over the columns
+      for (int i=0; i<m.rows(); ++i)    // loop over the rows
+        m(i,j) = i+j*m.rows();          // to access matrix elements use operator (int,int)
+    std::cout << m << "\n\n";
+  }
+
+  VectorXf v4(4);
+  // to access vector elements
+  // you can use either operator () or operator []
+  v4[0] = 1; v4[1] = 2; v4(2) = 3; v4(3) = 4;
+  std::cout << "\nv4:\n" << v4 << std::endl;
+}

doc/examples/Tutorial_simple_example_fixed_size.cpp

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+#include <Eigen/Core>
+
+// import most common Eigen's types 
+USING_PART_OF_NAMESPACE_EIGEN
+
+int main(int argc, char *argv[])
+{
+  Matrix3f m3;
+  m3 << 1, 2, 3, 4, 5, 6, 7, 8, 9;
+  Matrix4f m4 = Matrix4f::Identity();
+  Vector4i v4(1, 2, 3, 4);
+
+  std::cout << "m3\n" << m3 << "\nm4:\n" << m4 << "\nv4:\n" << v4 << std::endl;
+}