Fix issue #7245: update docs referring to calibration_api.ipynb (#7253)

The calibration notebook was deleted in #6580.

Author: mhucka

docs/google/best_practices.ipynb

@@ -525,7 +525,6 @@
     "\n",
     "For more on calibration and detailed instructions on how to perform these procedures, see the following tutorials:\n",
     "\n",
-    "* [Calibration API](../noise/calibration_api.ipynb)\n",
     "* [Floquet calibration example](../noise/floquet_calibration_example.ipynb)\n",
     "* [XEB calibration example](../noise/qcvv/xeb_calibration_example.ipynb)"
    ]

docs/noise/qcvv/coherent_vs_incoherent_xeb.ipynb

@@ -822,7 +822,7 @@
     "id": "E4xIRDi9gBnu"
    },
    "source": [
-    "In the coherent error case, the optimization was able to refit the fidelities very well. The new curves of the refit data almost perfectly match the horizontal line at `1.0` fidelity. The success of this refit means that the estimated parameters for this case are very likely to represent the actual parameters of the gate operation used, which was seen in the fact that the optimization re-discovered the `phi` value that was originally used to perturb `SQRT_ISWAP`. In the real hardware case, identifying these parameters means identifying what unitary the gate control hardware actually implemented. If this unitary is far from the intended one, hardware re-calibration or [compensation](../calibration_api.ipynb) must be performed in order to improve circuit fidelity. \n",
+    "In the coherent error case, the optimization was able to refit the fidelities very well. The new curves of the refit data almost perfectly match the horizontal line at `1.0` fidelity. The success of this refit means that the estimated parameters for this case are very likely to represent the actual parameters of the gate operation used, which was seen in the fact that the optimization re-discovered the `phi` value that was originally used to perturb `SQRT_ISWAP`. In the real hardware case, identifying these parameters means identifying what unitary the gate control hardware actually implemented. If this unitary is far from the intended one, hardware re-calibration or compensation must be performed in order to improve circuit fidelity. \n",
     "\n",
     "In constrast, the optimizer was completely unable to refit the circuit fidelities in the incoherent error case. The refit fidelities find no meaningful fidelity improvement, instead following the same, expected `5e-3` exponential decay as the original fidelities. Unsurprisingly, the optimizer was unable to find any coherent error in the incoherent-only fidelity data. \n",
     "\n",
@@ -889,7 +889,7 @@
     "## What's Next?\n",
     "\n",
     "Now that you've identified coherent error, what can you do about it? \n",
-    "- Depending on the parameter(s) identified to be out of tune, you may be able to change the circuits you want to run to compensate for that change. Read [Calibration API](../calibration_api.ipynb) for further information.\n",
+    "- Depending on the parameter(s) identified to be out of tune, you may be able to change the circuits you want to run to compensate for that change.\n",
     "- In the real hardware case, the device may need to be re-calibrated in order to fix the tuning of particular gate operations on particular qubits. Reach out to your Google contact to let us know!"
    ]
   }

docs/noise/qcvv/xeb_calibration_example.ipynb

@@ -70,7 +70,7 @@
     "id": "yKWtbKQB8Rej"
    },
    "source": [
-    "This tutorial shows a detailed example and benchmark of XEB calibration, a calibration technique introduced in the [Calibration: Overview and API](../calibration_api.ipynb) tutorial."
+    "This tutorial shows a detailed example and benchmark of Cross-Entropy Benchmarking (XEB) calibration."
    ]
   },
   {