[master] add request-nsid doc

3549.	[doc]		Documentation for "request-nsid" was missing.
			[RT #33153]

CHANGES

+3549.	[doc]		Documentation for "request-nsid" was missing.
+			[RT #33153]
+
 3548.	[bug]		The NSID request code in resolver.c was broken
 			resulting in invalid EDNS options being sent.
 			[RT #33153]

doc/arm/Bv9ARM-book.xml

@@ -5316,6 +5316,7 @@ badresp:1,adberr:0,findfail:0,valfail:0]
     <optional> multiple-cnames <replaceable>yes_or_no</replaceable>; </optional>
     <optional> notify <replaceable>yes_or_no</replaceable> | <replaceable>explicit</replaceable> | <replaceable>master-only</replaceable>; </optional>
     <optional> recursion <replaceable>yes_or_no</replaceable>; </optional>
+    <optional> request-nsid <replaceable>yes_or_no</replaceable>; </optional>
     <optional> rfc2308-type1 <replaceable>yes_or_no</replaceable>; </optional>
     <optional> use-id-pool <replaceable>yes_or_no</replaceable>; </optional>
     <optional> maintain-ixfr-base <replaceable>yes_or_no</replaceable>; </optional>
@@ -6739,6 +6740,22 @@ options {
               </listitem>
             </varlistentry>
 
+            <varlistentry>
+              <term><command>request-nsid</command></term>
+              <listitem>
+                <para>
+                  If <userinput>yes</userinput>, then an empty EDNS(0)
+                  NSID (Name Server Identifier) option is sent with all 
+                  queries to authoritative name servers during iterative
+                  resolution. If the authoritative server returns an NSID
+                  option in its response, then its contents are logged in
+                  the <command>resolver</command> category at level
+                  <command>info</command>.
+                  The default is <userinput>no</userinput>.
+                </para>
+              </listitem>
+            </varlistentry>
+
             <varlistentry>
               <term><command>rfc2308-type1</command></term>
               <listitem>