Update getting_started.ipynb

Typo correction in documentation.

Author: acolombi

docs/source/notebooks/getting_started.ipynb

@@ -1031,8 +1031,8 @@
     "$$ \n",
     "\\begin{aligned}  \n",
     "  D_t &\\sim \\text{Pois}(r_t), r_t= \\begin{cases} \n",
-    "   l, & \\text{if } t \\lt s \\\\\n",
-    "   e, & \\text{if } t \\ge s \n",
+    "   e, & \\text{if } t \\le s \\\\\n",
+    "   l, & \\text{if } t \\gr s \n",
     "   \\end{cases} \\\\\n",
     "  s &\\sim \\text{Unif}(t_l, t_h)\\\\         \n",
     "  e &\\sim \\text{exp}(1)\\\\\n",