added documentation for get_standard_gate_name_mapping (#13230)

* added documentation for get_standard_gate_name_mapping

* doc fix at line 145

* Update qiskit/circuit/library/__init__.py

Co-authored-by: Luciano Bello <bel@zurich.ibm.com>

* added docs get_standard_gate_name_mapping

* reformatting at line 65-66

* update fix formatting

* Update qiskit/circuit/library/standard_gates/__init__.py

Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

* docfix using autofunction

* content updated get_standard_gate_name_mapping

* Update qiskit/circuit/library/standard_gates/__init__.py

Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

* Update qiskit/circuit/library/__init__.py

Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

---------

Co-authored-by: Luciano Bello <bel@zurich.ibm.com>
Co-authored-by: Eric Arellano <14852634+Eric-Arellano@users.noreply.github.com>

Author: 3 people

qiskit/circuit/library/__init__.py

@@ -36,7 +36,11 @@
    circuit.append(gate, [0, 1, 4, 2, 3])
    circuit.draw('mpl')
 
-The library is organized in several sections.
+The library is organized in several sections. The function 
+:func:`.get_standard_gate_name_mapping` allows you to see the available standard gates and operations.
+
+.. autofunction:: get_standard_gate_name_mapping
+
 
 Standard gates
 ==============
@@ -126,6 +130,7 @@
    ZGate
    GlobalPhaseGate
 
+
 Standard Directives
 ===================
 
@@ -605,3 +610,4 @@
 from .grover_operator import GroverOperator, grover_operator
 from .phase_oracle import PhaseOracle
 from .overlap import UnitaryOverlap, unitary_overlap
+from .standard_gates import get_standard_gate_name_mapping

qiskit/circuit/library/standard_gates/__init__.py

@@ -48,7 +48,26 @@
 
 def get_standard_gate_name_mapping():
     """Return a dictionary mapping the name of standard gates and instructions to an object for
-    that name."""
+    that name.
+
+    Examples:
+
+        .. code-block:: python
+
+            from qiskit.circuit.library import get_standard_gate_name_mapping
+
+            gate_name_map = get_standard_gate_name_mapping()
+            cx_object = gate_name_map["cx"]
+
+            print(cx_object)
+            print(type(cx_object))
+
+        .. code-block:: text
+
+            Instruction(name='cx', num_qubits=2, num_clbits=0, params=[])
+            _SingletonCXGate
+    """
+
     from qiskit.circuit.parameter import Parameter
     from qiskit.circuit.measure import Measure
     from qiskit.circuit.delay import Delay