runtime(racket): Use shellescape() to harden the K mapping

fyi: @benknoble

Co-authored-by: Michał Majchrowicz <mmajchrowicz@afine.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/racket.vim

@@ -4,6 +4,7 @@
 " Previous Maintainer:  Will Langstroth <will@langstroth.com>
 " URL:                  https://github.com/benknoble/vim-racket
 " Last Change:          2025 Aug 09
+" 2026 Mar 31 by Vim project: use shellescape for the K mapping
 
 if exists("b:did_ftplugin")
   finish
@@ -51,7 +52,7 @@ if !exists("no_plugin_maps") && !exists("no_racket_maps")
     try
       let l:old_a = @a
       normal! gv"ay
-      call system("raco docs '". @a . "'")
+      call system("raco docs '". shellescape(@a) . "'")
       redraw!
       return @a
     finally