Update sample code [skip CI]

README.md

@@ -1,3 +1,58 @@
 Qibotn is the tensor-network translation module for Qibo to support large-scale simulation of quantum circuits and acceleration.
 
 To get started, `python setup.py install` to install the tools and dependencies.
+
+# Sample Codes
+## Single Node
+
+<pre>
+```
+import numpy as np
+from qibo import Circuit, gates
+import qibo
+
+'''
+computation_settings = {
+    'MPI_enabled': False,
+    'MPS_enabled': False,
+    'NCCL_enabled': False,
+    'expectation_enabled': {
+        'pauli_string_pattern': "IXZ"
+    }
+}
+'''
+
+computation_settings = {
+    'MPI_enabled': False,
+    'MPS_enabled': {
+                "qr_method": False,
+                "svd_method": {
+                    "partition": "UV",
+                    "abs_cutoff": 1e-12,
+                },
+            } ,
+    'NCCL_enabled': False,
+    'expectation_enabled': False
+}
+
+# computation_settings = {
+#     'MPI_enabled': False,
+#     'MPS_enabled': True,
+#     'NCCL_enabled': False,
+#     'expectation_enabled': False
+# }
+
+qibo.set_backend(backend="qibotn", runcard=computation_settings)
+
+# Construct the circuit
+c = Circuit(2)
+# Add some gates
+c.add(gates.H(0))
+c.add(gates.H(1))
+
+# Execute the circuit and obtain the final state
+result = c()
+
+print(result.state())
+```
+</pre>