add codepict sample

beautiful-racket/br/demo/jsonic/codepict.rkt

@@ -0,0 +1,12 @@
+#lang at-exp racket
+(require pict/code)
+(codeblock-pict
+    #:keep-lang-line? #f
+    @string-append|{
+                   #lang br/demo/jsonic
+{
+"string": @$(string-append "foo" "bar")$@,
+"array": @$(range 5)$@,
+"object": @$(hash "k1" "valstring" (format "~a" 42) (hash "k1" (range 10) "k2" 42))$@
+// "bar" :
+}|)