recipe: add exists? function

recipes/find-if-element-exists-in-list.md

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+# Test whether a given property exists in a sequence of N lists
+
+## Problem
+
+I have sequence of lists and I want to check if the lists have single element
+that return true when using given comparator.
+
+## Solution
+
+```scheme
+(define (exists? p . a*)
+  (letrec
+    ((car-of
+       (lambda (a)
+         (map car a)))
+     (cdr-of
+       (lambda (a)
+         (map cdr a)))
+     (any-null
+       (lambda (a)
+         (memq '() a)))
+     (exists*
+       (lambda (a*)
+         (and (not (any-null a*))
+              (or (apply p (car-of a*))
+                  (exists* (cdr-of a*)))))))
+    (exists* a*)))
+```
+
+Credit: [Nils M. Holm](http://t3x.org) (ref: [exists.scm](http://t3x.org/s9fes/exists.scm.html)
+
+## Usage
+
+```scheme
+(exists < '(9 1) '(8 2) '(7 3))
+;; ==>  #t because (< 1 2 3)
+```