patch 8.1.0117: URL in install program still points to SourceForge

Problem:    URL in install program still points to SourceForge.
Solution:   Change it to www.vim.org. (closes #3100)
diff --git a/src/dosinst.c b/src/dosinst.c
index e5d1f75..64edbbd 100644
--- a/src/dosinst.c
+++ b/src/dosinst.c
@@ -1878,7 +1878,7 @@
 	add_pathsep(shell_folder_path);
 	strcat(shell_folder_path, "Vim Online.url");
 	if (!WritePrivateProfileString("InternetShortcut", "URL",
-				     "http://vim.sf.net/", shell_folder_path))
+				    "https://www.vim.org/", shell_folder_path))
 	{
 	    printf("Creating the Vim online URL failed\n");
 	    return;