docs fix: add badges to __init__ so that docs include the badges (#1522)

Author: slayoo

docs/bibliography.json

@@ -766,7 +766,8 @@
   },
   "https://doi.org/10.1016/B978-0-444-42225-5.50008-5": {
     "usages": [
-      "examples/PySDM_examples/Gonfiantini_1986/fig_3_1.ipynb"
+      "examples/PySDM_examples/Gonfiantini_1986/fig_3_1.ipynb",
+      "examples/PySDM_examples/Gonfiantini_1986/__init__.py"
     ],
     "title": "Environmental isotopes in lake stadies",
     "label": "Gonfiantini 1986 (The Terrestrial Environment, B)"

examples/PySDM_examples/Gonfiantini_1986/__init__.py

@@ -0,0 +1,9 @@
+# pylint: disable=invalid-name
+"""
+Formulae-only example depicting Rayleigh fractionation from a flat surface of water
+ at different humidities for Oxygen-18 and Deuterium, based on
+[Gonfiantini 1986](https://doi.org/10.1016/B978-0-444-42225-5.50008-5)
+
+fig_3_1.ipynb:
+.. include:: ./fig_3_1.ipynb.badges.md
+"""