fix custom_jvp docs typo

docs/notebooks/Custom_derivative_rules_for_Python_code.ipynb

@@ -512,7 +512,7 @@
     "id": "l_6tdb-QGK-H"
    },
    "source": [
-    "Consider the function $f : \\mathbb{R}_+ \\mapsto \\mathbb{R}_+$ with $f(x) = \\frac{x}{1 + \\sqrt{x}}$, where we take $\\mathbb{R}_+ = [0, \\infty)$. We might implement $f$ as a program like this:"
+    "Consider the function $f : \\mathbb{R}_+ \\to \\mathbb{R}_+$ with $f(x) = \\frac{x}{1 + \\sqrt{x}}$, where we take $\\mathbb{R}_+ = [0, \\infty)$. We might implement $f$ as a program like this:"
    ]
   },
   {

docs/notebooks/Custom_derivative_rules_for_Python_code.md

@@ -270,7 +270,7 @@ A related application is to enforce a differentiation convention, perhaps at a b
 
 +++ {"id": "l_6tdb-QGK-H"}
 
-Consider the function $f : \mathbb{R}_+ \mapsto \mathbb{R}_+$ with $f(x) = \frac{x}{1 + \sqrt{x}}$, where we take $\mathbb{R}_+ = [0, \infty)$. We might implement $f$ as a program like this:
+Consider the function $f : \mathbb{R}_+ \to \mathbb{R}_+$ with $f(x) = \frac{x}{1 + \sqrt{x}}$, where we take $\mathbb{R}_+ = [0, \infty)$. We might implement $f$ as a program like this:
 
 ```{code-cell} ipython3
 :id: AfF5P7x_GaSe