patch 8.1.0473: user doesn't notice file does not exist when swap file does

Problem:    User doesn't notice file does not exist when swap file does.
Solution:   Add a note that the file cannot be found.  Make the "still
            running" notice stand out.
diff --git a/src/version.c b/src/version.c
index 1d1c1b2..995adff 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    473,
+/**/
     472,
 /**/
     471,