patch 9.1.0512: Mode message for spell completion doesn't match allowed keys

Problem:  Mode message for spell completion doesn't match allowed keys
          (Kyle Kovacs)
Solution: Show "^S" instead of "s".
          (zeertzjq)

This matches the code in vim_is_ctrl_x_key():

	case CTRL_X_SPELL:
	    return (c == Ctrl_S || c == Ctrl_P || c == Ctrl_N);

fixes: neovim/neovim#29431
closes: #15065

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index e0b0d5c..41d9281 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    512,
+/**/
     511,
 /**/
     510,