fix: Avoid sphinx error "Code Execution failed:NameError: name 'for…

…mat_locale' is not defined" (#3503)

doc/user_guide/customization.rst

@@ -823,14 +823,6 @@ The preferred format of numbers, dates, and currencies varies by language and lo
 Vega-Altair takes advantage of `D3's localization support`_ to make it easy to configure
 the locale for your chart using the global ``alt.renderers.set_embed_options`` function.
 
-.. altair-plot::
-   :output: none
-
-   import altair as alt
-   alt.renderers.set_embed_options(
-       format_locale=format_locale, time_format_locale=time_format_locale
-   )
-
 Here ``format_locale`` and ``time_format_locale`` may either be D3 format dictionaries,
 or strings with the names of pre-defined locales. For example, here we use the
 Italian locale (named ``it-IT``) for both currencies and dates: