Use fixed font in to_sentence API docs [ci skip]

Improves legibility.

**Before**

![before](https://github.com/user-attachments/assets/93ce34d3-34fd-47ca-bda2-f82674eea547)

**After**

![after](https://github.com/user-attachments/assets/54ea08c5-ac98-43ed-b0c6-d47c34e3eadf)

Author: claudiob

activesupport/lib/active_support/core_ext/array/conversions.rb

@@ -16,11 +16,11 @@ class Array
   # ==== Options
   #
   # * <tt>:words_connector</tt> - The sign or word used to join all but the last
-  #   element in arrays with three or more elements (default: ", ").
+  #   element in arrays with three or more elements (default: <tt>", "</tt>).
   # * <tt>:last_word_connector</tt> - The sign or word used to join the last element
-  #   in arrays with three or more elements (default: ", and ").
+  #   in arrays with three or more elements (default: <tt>", and "</tt>).
   # * <tt>:two_words_connector</tt> - The sign or word used to join the elements
-  #   in arrays with two elements (default: " and ").
+  #   in arrays with two elements (default: <tt>" and "</tt>).
   # * <tt>:locale</tt> - If +i18n+ is available, you can set a locale and use
   #   the connector options defined on the 'support.array' namespace in the
   #   corresponding dictionary file.