patch 8.1.2205: sign entry structure has confusing name

Problem:    Sign entry structure has confusing name.
Solution:   Rename signlist_T to sign_entry_T and prefix se_ to the fields.
diff --git a/src/version.c b/src/version.c
index 09e8ad3..057ab74 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2205,
+/**/
     2204,
 /**/
     2203,