Added comment to the placement example

  }

}

// Example: using ibmq_ourense (5 qubits) which has 

// Example: using ibmq_ourense or ibmqx2 (5 qubits) which has 

// the following connectivity graph:

// 0 -- 1 -- 2

//      |

//      3

//      |

//                         1

//                       / | 

//                      /  |

// 0 -- 1 -- 2         /   |

//      |             /    |

//      3            0 --  2  --  3

//      |                  |     /

//      4                  |    /

//                         |   / 

//                         |  /

//                         4

// Compile: qcor -qpu aer:ibmq_ourense simplePlacement.cpp 

// Compile: qcor -qpu aer:ibmqx2 simplePlacement.cpp  

// Make sure to have a valid ~/.ibm_config file.

// Example: 

// key: YOUR_API_KEY