Update URL to https://tuxpaint.org/ everywhere

Also, add other social media accounts to list of places to
announce Tux Paint in RELEASE docs.

Also, list a ton more options missing from default example config file
"src/tuxpaint.conf"

src/ios_print.h

@@ -1,8 +1,8 @@
 /*
   ios_print.h
 
-  Copyright (c) 2021
-  http://www.tuxpaint.org/
+  Copyright (c) 2021-2022
+  https://tuxpaint.org/
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,6 +18,8 @@
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   (See COPYING.txt)
+
+  Last updated: December 11, 2022
 */
 #ifndef __IOS_PRINT_H__
 #define __IOS_PRINT_H__