Fix img size and link

Fix image size and link to topological walk

Author: qubeat

awards/teach_me_qiskit_2018/state_distribution_in_qubit_chains/index.ipynb

@@ -5,7 +5,7 @@
    "metadata": {},
    "source": [
     "<img src=\"https://raw.githubusercontent.com/Qiskit/qiskit-tutorials/master/images/qiskit-heading.png\" alt=\"Qiskit\" align=\"left\">\n",
-    "<img src=\"images/qubit-chain-logo.png\" alt=\"Qubit Chain\" align=\"right\">"
+    "<img src=\"images/qubit-chain-logo.png\" alt=\"Qubit Chain\" width=\"500 px\" align=\"right\">"
    ]
   },
   {

awards/teach_me_qiskit_2018/state_distribution_in_qubit_chains/qubit_chain.ipynb

@@ -22,7 +22,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Here is used representation initially introduced for _perfect state transfer_. The chain with $n$ nodes is modeled by $n$ qubits. The more compact representation with $n$ qubits for a chain $N=2^n$ nodes is discussed elsewhere, _e.g._, see arXiv:1710.03615 \\[quant-ph\\](2017) with [tutorial about topological quantum walk](../../terra/qis_adv/topological_quantum_walk.ipynb).\n",
+    "Here is used representation initially introduced for _perfect state transfer_. The chain with $n$ nodes is modeled by $n$ qubits. The more compact representation with $n$ qubits for a chain $N=2^n$ nodes is discussed elsewhere, _e.g._, see arXiv:1710.03615 \\[quant-ph\\](2017) with [tutorial about topological quantum walk](../../../terra/qis_adv/topological_quantum_walk.ipynb).\n",
     "\n",
     "### Chain model\n",
     "\n",