Add editor comment about <span> for old anchor

index.bs

@@ -5777,6 +5777,8 @@ the wrong [=credential ID=], or if an attacker intercepts and manipulates the [=
 
 
 ## Security considerations for [=authenticators=] <span id="sctn-attestation-security-considerations"></span> ## {#sctn-security-considerations-authenticator}
+<!-- Note: the above <span> is there to preserve the #sctn-attestation-security-considerations anchor although the section it was
+tied to has been removed. The section had no text of its own and served only to group the following two subsections together. -->
 
 ### Attestation Certificate Hierarchy ### {#sctn-cert-hierarchy}