Update index for extended stabilizer (#604)

* add @chriseclectic to aer code owner

* update index for extended stabilizer

Author: chriseclectic

.github/CODEOWNERS

@@ -23,3 +23,5 @@ community/awards/teach_me_qiskit_2018/*/* @rraymondhp
 community/ignis/* @dcmckayibm
 qiskit/ignis/* @dcmckayibm
 
+community/aer/* @chriseclectic
+qiskit/aer/* @chriseclectic

index.ipynb

@@ -66,10 +66,11 @@
     "\n",
     "Aer, the ‘air’ element, permeates all Qiskit elements. To really speed up development of quantum computers we need better simulators with the ability to model realistic noise processes that occur during computation on actual devices. Aer provides a high-performance simulator framework for studying quantum computing algorithms and applications in the noisy intermediate scale quantum regime. \n",
     "  * [Aer provider](qiskit/aer/aer_provider.ipynb) - gives a summary of the Qiskit Aer provider containing the Qasm, statevector, and unitary simulator.\n",
+    "  * [Extended stabilizer tutorial](qiskit/aer/extended_stabilizer_tutorial.ipynb) - gives an overview of the *extended stabilizer* Qasm Simulator method.\n",
     "  * [Device noise simulation](qiskit/aer/device_noise_simulation.ipynb) - shows how to use the Qiskit Aer noise module to automatically generate a basic noise model for simulating hardware backends.\n",
     "  * [Building noise models](qiskit/aer/building_noise_models.ipynb) - shows how to use Qiskit Aer noise module to construct custom noise models for noisy simulations.\n",
     "  * [Custom gate noise](qiskit/aer/custom_gate_noise.ipynb) - shows to implement simulations using custom noisy gates.\n",
-    "  * [Noise transformations](qiskit/aer/noise_transformation.ipynb) - demonstrates the noise approximation utility functions to construct approximate Clifford noise models out of general noise model.\n",
+    "  * [Noise transformations](qiskit/aer/noise_transformation.ipynb) - demonstrates the noise approximation utility functions to construct approximate Clifford noise models out of a general noise model.\n",
     "  \n",
     "####  1.5 Qiskit Ignis\n",
     "Ignis, the ‘fire’ element, is dedicated to fighting noise and errors and to forging a new path. This includes better characterization of errors, improving gates, and computing in the presence of noise. Ignis is meant for those who want to design quantum error correction codes, or who wish to study ways to characterize errors through methods such as tomography, or even to find a better way for using gates by exploring dynamical decoupling and optimal control. While we have already released parts of this element as part of libraries in Terra, an official stand-alone release will come soon. For now we have some tutorials for you to explore.\n",