patch 8.2.1128: the write message mentions characters, but it's bytes

Problem:    The write message mentions characters, but it's actually bytes.
Solution:   Change "C" to "B" and "characters" to "bytes".
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index bd6cc62..109fc16 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -6730,7 +6730,7 @@
 	 flag	meaning when present	~
 	  f	use "(3 of 5)" instead of "(file 3 of 5)"
 	  i	use "[noeol]" instead of "[Incomplete last line]"
-	  l	use "999L, 888C" instead of "999 lines, 888 characters"
+	  l	use "999L, 888B" instead of "999 lines, 888 bytes"
 	  m	use "[+]" instead of "[Modified]"
 	  n	use "[New]" instead of "[New File]"
 	  r	use "[RO]" instead of "[readonly]"