improve HTML menus, add social.html, prep for IOCCC28 winners

Prepare for the winners of **IOCCC28**.

> However these are not the 2024 droids you are looking for.  :-)

The HTML menu (both JavaScript and non-JavaScript) has been updated.

The `Status -> Rules and guidelines' have been replaced with two
separate menus `Status -> IOCCC rules` and `Status -> IOCCC guidelines`.

Added a new top level `social.html` page: built from a new `social.md`.

Sorted rules for building specific web pages in the top level `Makefile`.
Added `make social` to make the `social.html` page from `social.md`.

The `bin/gen-top-html.sh` now is able to process a argument of **social**
to process the new top level `social.html` page.

Changed `bin/gen-top-html.sh` VERSION from "2.0.0 2025-03-13"
to "2.0.1 2025-07-25".

Below `About -> Home page` a new `About -> IOCCC social media` menu item
as added.

Because the menu change touched every HTML file, we changed the general
copyright date range for HTML files from "1984-2024" to "1984-2025"
due to the extensive changes made for **IOCCC28**.

Those markdown files that were modified in 2025 had their copyright date
range also changed from "1984-2024" to "1984-2025".

Rebuilt tarballs and sitemap due to the extensive HTML rebuilding.

Ran `make update` to perform the above.

bin/gen-top-html.sh

@@ -124,7 +124,7 @@ export LC_ALL="C"
 
 # set variables referenced in the usage message
 #
-export VERSION="2.0.0 2025-03-13"
+export VERSION="2.0.1 2025-07-25"
 NAME=$(basename "$0")
 export NAME
 export V_FLAG=0
@@ -174,6 +174,7 @@ TOP_MD_SET+=("nojs-menu")
 TOP_MD_SET+=("quick-start")
 TOP_MD_SET+=("README")
 TOP_MD_SET+=("SECURITY")
+TOP_MD_SET+=("social")
 TOP_MD_SET+=("status")
 TOP_MD_SET+=("thanks-for-help")
 declare -ag TOP_MD_SELECT_SET