Add link to openmc.org/depletion-chains in example notebook

examples/jupyter/pincell_depletion.ipynb

@@ -339,7 +339,10 @@
     "* A fission event for U-235 produces fission products like Xe135 according to a distribution\n",
     "* For thermal problems, Am241 will produce metastable Am242 about 8% of the time during an $(n,\\gamma)$ reaction. The other 92% of capture reactions will produce ground state Am242\n",
     "\n",
-    "These data are often distributed with other nuclear data, like incident neutron cross sections with ENDF/B-VII. The `openmc.deplete.Chain` object is responsible for representing this information. Two executables, `openmc-make-depletion-chain` and `openmc-make-depletion-chain-casl` will read in nuclear data using the `OPENMC_ENDF_DATA` environment variable and produce two depletion chain files. The first is a more detailed file containing every reaction and fission product possible, while the second uses data from CASL [Specification for the VERA Depletion Benchmark Suite](https://doi.org/10.2172/1256820) report to reduce the number of isotopes.\n",
+    "These data are often distributed with other nuclear data, like incident neutron cross sections with ENDF/B-VII.\n",
+    "OpenMC uses the [`openmc.deplete.Chain`](https://docs.openmc.org/en/latest/pythonapi/generated/openmc.deplete.Chain.html#openmc.deplete.Chain) to collect represent the various decay and transmutation pathways in a single object.\n",
+    "While a complete `Chain` can be created using nuclear data files, users may prefer to download pre-generated XML-representations instead.\n",
+    "Such files can be found at https://openmc.org/depletion-chains/ and include full and compressed chains, with capture branching ratios derived using PWR- or SFR-spectra.\n",
     "\n",
     "For this problem, we will be using a much smaller depletion chain that contains very few nuclides. In a realistic problem, over 1000 isotopes may be included in the depletion chain."
    ]