docs: update README.md with new content

scripts/dossiers-ngi/caddy-dossiers-ngi.snippet

@@ -0,0 +1,19 @@
+# Stanza body for dossiers.ngi.hacktivism.ch only (hand-check / re-seed).
+# Templates apply is host-local on koopa (not in this repo):
+#   bash ~/bin/apply-dossiers-ngi-templates.sh
+#   sudo ~/bin/caddy-apply
+#
+# Keep the existing line: header Alt-Svc "clear"
+# Keep any existing basic_auth in that same block.
+# scripts/caddy/caddy-apply.sh --snippet reports an existing block and
+# does not merge these lines. Leave that script unused for this change.
+# Leave scripts/caddy/apply-goa-wdGet-full-replace.sh unused.
+# Leave scripts/caddy/apply-dossiers-ngi-basicauth.sh unused.
+# Stock Caddy templates only. No replace-response plugin.
+#
+# Tab-indented lines inserted after header Alt-Svc:
+
+	templates {
+		mime text/html
+		between "{%" "%}"
+	}