MINOR: Add links to connector configs in TOC
Reviewers: Luke Chen Andrew Eugene Choi
<li><a href="#producerconfigs">3.3 Producer Configs</a>
<li><a href="#consumerconfigs">3.4 Consumer Configs</a>
<li><a href="#connectconfigs">3.5 Kafka Connect Configs</a>
+ <ul>
+ <li><a href="#sourceconnectconfigs">Source Connector Configs</a>
+ <li><a href="#sinkconnectconfigs">Sink Connector Configs</a>
+ </ul>
<li><a href="#streamsconfigs">3.6 Kafka Streams Configs</a>
<li><a href="#adminclientconfigs">3.7 AdminClient Configs</a>
</ul>
