feat: Add highlight config for trailing white spaces in yaml files

lua/plugins/astroui.lua

@@ -1,4 +1,4 @@
-if true then return {} end -- WARN: REMOVE THIS LINE TO ACTIVATE THIS FILE
+-- if true then return {} end -- WARN: REMOVE THIS LINE TO ACTIVATE THIS FILE
 
 -- AstroUI provides the basis for configuring the AstroNvim User Interface
 -- Configuration documentation can be found with `:h astroui`
@@ -16,6 +16,7 @@ return {
     highlights = {
       init = { -- this table overrides highlights in all themes
         -- Normal = { bg = "#000000" },
+        TrailingWhiteSpace = { bg = "red" },
       },
       astrodark = { -- a table of overrides/changes when applying the astrotheme theme
         -- Normal = { bg = "#000000" },