MINOR: Fix typo on introduction page

Author: ash <ashishg@qburst.com>

Reviewers: Guozhang Wang <wangguoz@gmail.com>

Closes #2259 from ashishg-qburst/intro

docs/introduction.html

@@ -41,7 +41,7 @@
   <p>Kafka has four core APIs:</p>
   <div style="overflow: hidden;">
       <ul style="float: left; width: 40%;">
-      <li>The <a href="/documentation.html#producerapi">Producer API</a> allows an application to publish a stream records to one or more Kafka topics.
+      <li>The <a href="/documentation.html#producerapi">Producer API</a> allows an application to publish a stream of records to one or more Kafka topics.
       <li>The <a href="/documentation.html#consumerapi">Consumer API</a> allows an application to subscribe to one or more topics and process the stream of records produced to them.
     <li>The <a href="/documentation.html#streams">Streams API</a> allows an application to act as a <i>stream processor</i>, consuming an input stream from one or more topics and producing an output stream to one or more output topics, effectively transforming the input streams to output streams.
     <li>The <a href="/documentation.html#connect">Connector API</a> allows building and running reusable producers or consumers that connect Kafka topics to existing applications or data systems. For example, a connector to a relational database might capture every change to a table.