MINOR Clarified maximum length of COMPACT_STRING

Author: josefk31

clients/src/main/java/org/apache/kafka/common/protocol/types/Type.java

@@ -549,7 +549,8 @@ public String validate(Object item) {
         @Override
         public String documentation() {
             return "Represents a sequence of characters. First the length N + 1 is given as an UNSIGNED_VARINT " +
-                    ". Then N bytes follow which are the UTF-8 encoding of the character sequence.";
+                    ". Then N bytes follow which are the UTF-8 encoding of the character sequence. " +
+                    "The maximum length of a compact string is 32767.";
         }
     };