propagate from branch 'i2p.www' (head 114708fc5836389206fe26e04905a1887f34a228)

to branch 'i2p.www.revamp' (head 061377e9345d8848b120576d4174d4274a2e5ca3)

i2p2www/pages/site/docs/spec/common-structures.html

@@ -612,7 +612,10 @@ Cost is typically 5 or 6 for SSU, and 10 or 11 for NTCP.
 {%- endtrans %}</li>
 
 <li>{% trans -%}
-Expiration is currently unused, always null (all zeroes))
+Expiration is currently unused, always null (all zeroes)).
+As of release 0.9.3, the expiration is assumed zero and not stored, so any non-zero expiration
+will fail in the RouterInfo signature verification.
+Implementing expiration (or another use for these bytes) will be a backwards-incompatible change.
 {%- endtrans %}</li>
 </ul>