Remove lost reference to the random number generator.

source/code_topics.Rmd

@@ -47,7 +47,6 @@ list as a whole, as here.
 * Selecting multiple elements from {{< var array >}}s with slicing: @sec-slice-indexing.
 * Strings — values containing text: @sec-intro-to-strings.
 * Randomness from your computer: @sec-randomness-computer.
-* Numpy's random number generator: @nte-numpy-rng.
 * Types of brackets in {{< var lang >}}: @nte-bracket-types.
 * Squaring values and {{< var array >}}s: @sec-squared-arrays.
 * Introducing functions: @sec-introducing-functions.