Improve "CRAM version 4.0 is still draft" wording

In particular, shorten to two lines and improve the line break.

Author: jmarshall

cram/cram_io.c

@@ -5688,10 +5688,9 @@ int cram_set_voption(cram_fd *fd, enum hts_fmt_option opt, va_list args) {
 
         if (major > 3 || (major == 3 && minor > 0)) {
             hts_log_warning(
-                "CRAM version %s is still in draft and is subject to\n"
-                "change. Please consider this a technology demonstration "
-                "and do not use for\n"
-                "long term archival of data.", s);
+                "CRAM version %s is still a draft and subject to change.\n"
+                "This is a technology demonstration that should not be "
+                "used for archival data.", s);
         }
 
         fd->version = major*256 + minor;