minor #2107 [Doc] Fix a Twig function name in UX Map docs (javiereguiluz)

This PR was squashed before being merged into the 2.x branch.

Discussion
----------

[Doc] Fix a Twig function name in UX Map docs

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Issues        | -
| License       | MIT

I've started using the UX Map component in a Symfony app. So far it's great, thanks. I found a minor error in the docs about the name of the function to use.

Commits
-------

80ee61d [Doc] Fix a Twig function name in UX Map docs

Author: javiereguiluz

src/Map/doc/index.rst

@@ -124,11 +124,12 @@ To render a map in your Twig template, use the ``ux_map`` Twig function, e.g.:
 
 .. code-block:: twig
 
-    {{ ux_map(my_map) }}
-    
-    {# or with custom attributes #}
+    {# to be visible, the map must have a defined height #}
     {{ ux_map(my_map, { style: 'height: 300px' }) }}
 
+    {# you can add custom HTML attributes too #}
+    {{ ux_map(my_map, { style: 'height: 300px', id: 'events-map', class: 'mb-3' }) }}
+
 Extend the default behavior
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~