patch 8.0.0724: the message for yanking doesn't indicate the register

Problem:    The message for yanking doesn't indicate the register.
Solution:   Show the register name in the "N lines yanked" message. (Lemonboy,
            closes #1803, closes #1809)
diff --git a/src/version.c b/src/version.c
index 1b2cc8a..e8e2e05 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    724,
+/**/
     723,
 /**/
     722,