fix arviz link (#4208)

Author: cranmer

docs/source/notebooks/api_quickstart.ipynb

@@ -998,7 +998,7 @@
     "\n",
     "The main entry point to MCMC sampling algorithms is via the `pm.sample()` function. By default, this function tries to auto-assign the right sampler(s) and auto-initialize if you don't pass anything.\n",
     "\n",
-    "With PyMC3 version >=3.9 the `return_inferencedata=True` kwarg makes the `sample` function return an `arviz.InferenceData` object instead of a `MultiTrace`. `InferenceData` has many advantages, compared to a `MultiTrace`: For example it can be saved/loaded from a file, and can also carry additional (meta)data such as date/version, or posterior predictive distributions. Take a look at the [ArviZ Quickstart](https://arviz-devs.github.io/arviz/notebooks/Introduction.html) to learn more."
+    "With PyMC3 version >=3.9 the `return_inferencedata=True` kwarg makes the `sample` function return an `arviz.InferenceData` object instead of a `MultiTrace`. `InferenceData` has many advantages, compared to a `MultiTrace`: For example it can be saved/loaded from a file, and can also carry additional (meta)data such as date/version, or posterior predictive distributions. Take a look at the [ArviZ Quickstart](https://arviz-devs.github.io/arviz/getting_started/Introduction.html) to learn more."
    ]
   },
   {
@@ -2325,7 +2325,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.7"
+   "version": "3.6.8"
   }
  },
  "nbformat": 4,