Provide more details for new committers on Bugzilla account merging

Update Bugzilla section of new committer's guide with more detailed
description of Bugzilla account merging and add reference to Kerberos
password generation/change. Based on emails bugmeister@ team receives these
items are the most common sources of confusion for new FeeBSD committers
when it comes to bugtracker.

Reviewed by:	mat
Differential Revision:	https://reviews.freebsd.org/D12828

en_US.ISO8859-1/articles/committers-guide/article.xml

@@ -2981,9 +2981,34 @@ Relnotes:           yes</programlisting>
       non-<systemitem class="domainname">&os;.org</systemitem>
       Bugzilla accounts can have the old account merged with the
       <systemitem class="domainname">&os;.org</systemitem> account by
-      entering a new bug.  Choose
-      <literal>Supporting Services</literal> as the Product, and
-      <literal>Bug Tracker</literal> as the Component.</para>
+      following these steps:</para>
+
+      <procedure>
+        <step>
+	  <para>Log in using your old account.</para>
+	</step>
+
+        <step>
+          <para>Open new bug.  Choose
+            <literal>Supporting Services</literal> as the Product, and
+            <literal>Bug Tracker</literal> as the Component.
+	    In bug description list acounts you wish to be merged.</para>
+	</step>
+
+        <step>
+	  <para>Log in using
+	    <systemitem class="domainname">&os;.org</systemitem> account and
+	    post comment to newly opened bug to confirm ownership.  See
+	    <xref linkend="kerberos-ldap"/> for more details on how to
+	    generate or set a password for your
+	    <systemitem class="domainname">&os;.org</systemitem> account.</para>
+        </step>
+
+        <step>
+	  <para>If there are more than two accounts to merge, post
+	    comments from each of them.</para>
+        </step>
+      </procedure>
 
     <para>You can find out more about
       <application>Bugzilla</application> at:</para>