[meld] Update README with correct help URL

[Kai Willadsen <kaiw src gnome org>]

commit ebce1bda5e9922e8b0a722d73b3c89327efb61af
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Sep 4 10:13:14 2022 +1000

    Update README with correct help URL
    
    Ideally we'd redirect to this as well, but that's not possible with the
    current deployment method.

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index 63486e07..77009f8b 100644
--- a/README.md
+++ b/README.md
@@ -119,6 +119,6 @@ Links
 
 Home page:      http://meldmerge.org
 
-Documentation:  http://meldmerge.org/help
+Documentation:  http://meldmerge.org/help/
 
 Wiki:           https://wiki.gnome.org/Apps/Meld