fix typo! in r-objects.html

docs/r-objects.html

@@ -972,7 +972,7 @@ <h2><span class="header-section-number">5.9</span> Loading Data</h2>
 ## eight spades     8</code></pre>
 
 <div class="rmdnote">
-<code>head</code> and <code>tail</code> are two functions that provide an easy way to peek at large data sets. <code>head</code> will return just the first six rows of the data set, and <code>tail</code> will return just the last six rows. To see a different number of rows, give <code>head</code> or <code>tails</code> a second argument, the number of rows you would like to view, for example, <code>head(deck, 10)</code>.
+<code>head</code> and <code>tail</code> are two functions that provide an easy way to peek at large data sets. <code>head</code> will return just the first six rows of the data set, and <code>tail</code> will return just the last six rows. To see a different number of rows, give <code>head</code> or <code>tail</code> a second argument, the number of rows you would like to view, for example, <code>head(deck, 10)</code>.
 </div>
 
 <p>R can open many types of files—not just CSVs. Visit <a href="dataio.html#dataio">Loading and Saving Data in R</a> to learn how to open other common types of files in R.</p>