improve use of Support the IOCCC, Social Media code blocks

Changed "Support IOCCC" heading to "Support the IOCCC".

Use HTML blockquote instead of markdown quote for the "Support the IOCCC"
and "IOCCC on Social Media" HTML code blocks.

Added "Support the IOCCC" and "IOCCC on Social Media" to the
top level `index.html` page, the top level `news.html` page and
the top level `years.html` page.

Changed `bin/gen-years.sh` VERSION from "2.0.0 2025-03-13"
to "2.1.0 2025-06-06".

Update sitemap.

Tested the above via `make gen_top_html gen_years timestamp` on macOS.

years.html

@@ -431,6 +431,48 @@
 <a href="#1994">1994</a> | <a href="#1993">1993</a> | <a href="#1992">1992</a> | <a href="#1991">1991</a> | <a href="#1990">1990</a> | <a href="#1989">1989</a> | <a href="#1988">1988</a> | <a href="#1987">1987</a><br><br>
 <a href="#1986">1986</a> | <a href="#1985">1985</a> | <a href="#1984">1984</a></p>
 <p><a href="#year_level"><strong>Year level tarballs</strong></a></p>
+<blockquote>
+<table>
+<tr>
+<td colspan="3" style="padding-top: 12px;">
+<span class="pseudo_h3">  IOCCC on Social Media</span>
+<span class="small_click_below">   click below to visit</span>
+</td>
+</tr>
+<tr>
+<td>
+    <a href="https://patreon.com/IOCCC"><img src="png/patreon.128x19.png" alt="Patreon logo" width=128 height=19></a>
+</td>
+<td>
+    <a href="https://coff.ee/ioccc"><img src="png/buymeacoffee.128x38.png" alt="Buy Me A Coffee logo" width=128 height=38></a>
+</td>
+<td>
+    <a href="https://github.com/sponsors/ioccc-src"><img src="png/GitHub.128x51.png" alt="GitHub logo" width=128 height=51></a>
+</td>
+</tr>
+</table>
+</blockquote>
+<blockquote>
+<table>
+<tr>
+<td colspan="3" style="padding-top: 12px;">
+<span class="pseudo_h3">  IOCCC on Social Media</span>
+<span class="small_click_below">   click below to visit</span>
+</td>
+</tr>
+<tr>
+<td style="padding-top: 8px;">
+    <a href="https://discord.gg/Wa42Qujwnw"><img src="png/Discord.128x37.png" alt="Discord logo" width=128 height=37></a>
+</td>
+<td style="padding-top: 12px; padding-bottom: 3px;">
+    <a href="https://fosstodon.org/@ioccc"><img src="png/mastodon.128x38.png" alt="Mastodon logo" width=128 height=38></a>
+</td>
+<td>
+    <a href="https://www.youtube.com/@OurFavoriteUniverse"><img src="png/YouTube.128x46.png" alt="YouTube logo" width=128 height=46></a>
+</td>
+</tr>
+</table>
+</blockquote>
 <div id="2020">
 <h2 id="the-27th-ioccc">2020 - The 27th IOCCC</h2>
 <a class="normal" href="2020/index.html">About the 27th IOCCC (2020)</a><br>