[QAOA] Documents Changes

.github/CHANGELOG.md

@@ -87,6 +87,22 @@
 * Added an `ApproxTimeEvolution` template to the PennyLane templates module, which 
   can be used to implement Trotterized time-evolution under a Hamiltonian.
   [(#710)](https://github.com/XanaduAI/pennylane/pull/710)
+
+* Added a `qml.layer` template-constructing function, which takes a unitary, and 
+  repeatedly applies it on a set of wires to a given depth.
+  [(#723)](https://github.com/PennyLaneAI/pennylane/pull/723)
+
+* Added built-in QAOA functionality to PennyLane. This includes the following features:
+    * Added `qml.qaoa.x_mixer` and `qml.qaoa.xy_mixer` methods for defining Pauli-X and XY 
+      mixer Hamiltonians.
+      [(#712)](https://github.com/PennyLaneAI/pennylane/pull/712)
+    * Added the `qml.qaoa.maxcut` method, which allows the user to get the cost Hamiltonian 
+      and recommended mixer Hamiltonian for QAOA MaxCut, for a supplied graph.
+      [(#718)](https://github.com/PennyLaneAI/pennylane/pull/718)
+      [(#741)](https://github.com/PennyLaneAI/pennylane/pull/741)
+    * Added `qml.qaoa.cost_layer` and `qml.qaoa.mixer_layer`, which take cost and mixer Hamiltonians, 
+      respectively, and apply the corresponding QAOA cost and mixer layers. 
+      [(#720)](https://github.com/PennyLaneAI/pennylane/pull/720)
 
 <h3>Improvements</h3>
 

doc/code/qml_qaoa.rst

@@ -3,7 +3,26 @@ qml.qaoa
 
 .. currentmodule:: pennylane.qaoa
 
-.. automodapi:: pennylane.qaoa
+Mixer Hamiltonians
+------------------
+
+.. automodapi:: pennylane.qaoa.mixers
+    :no-heading:
+    :no-inheritance-diagram:
+    :no-inherited-members:
+
+Cost Hamiltonians
+-----------------
+
+.. automodapi:: pennylane.qaoa.cost
+    :no-heading:
+    :no-inheritance-diagram:
+    :no-inherited-members:
+
+QAOA Layers
+-----------
+
+.. automodapi:: pennylane.qaoa.layers
     :no-heading:
     :no-inheritance-diagram:
-    :no-inherited-members:
+    :no-inherited-members:

pennylane/qaoa/cost.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 r"""
-This file contains functions that generate QAOA cost Hamiltonians corresponding to
+Methods for generating QAOA cost Hamiltonians corresponding to
 different optimization problems.
 """
 

pennylane/qaoa/mixers.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 r"""
-This file contains built-in functions for constructing QAOA mixer Hamiltonians.
+Methods for constructing QAOA mixer Hamiltonians.
 """
 import networkx as nx
 import pennylane as qml