Add computer specs to notebook

Author: gmingas

docs/source/notebooks/MLDA_multilevel_groundwater_flow.ipynb

@@ -22,6 +22,8 @@
     "\n",
     "Please note that the MLDA sampler is new in pymc3. The user should be extra critical about the results and report any problems as issues in the pymc3's github repository.\n",
     "\n",
+    "The notebook results shown below were generated on a MacBook Pro with a 2.6 GHz 6-core Intel Core i7, 32 GB DDR4 and macOS 10.15.4.\n",
+    "\n",
     "### The model\n",
     "Within this notebook, a simple MLDA sampler is compared to pymc3's Metropolis MCMC sampler. The target posterior is defined within the context of a Bayesian inverse problem for groundwater flow modeling, where we solve a PDE in each likelihood evaluation and we are able to do this in different coarseness levels.\n",
     "\n",