docs: add lastmod dates to sitemap.xml

Author: manojmallick

docs/sitemap.xml

@@ -2,51 +2,61 @@
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
   <url>
     <loc>https://manojmallick.github.io/sigmap/</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/quick-start.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/cli.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/config.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/mcp.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/troubleshooting.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.8</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/strategies.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.8</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/languages.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.7</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/repomix.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.7</priority>
   </url>
   <url>
     <loc>https://manojmallick.github.io/sigmap/roadmap.html</loc>
+    <lastmod>2026-04-04</lastmod>
     <changefreq>monthly</changefreq>
     <priority>0.6</priority>
   </url>