Fix spelling error in docs

docs/buildroot.html

@@ -213,7 +213,7 @@ $ make HOSTCXX=g++-4.3-HEAD HOSTCC=gcc-4.3-HEAD
 $ complete -W menuconfig make
 </pre>
 
-    <p>Then just enter the begining of the line, and ask <i>bash</i> to
+    <p>Then just enter the beginning of the line, and ask <i>bash</i> to
     complete it for you by pressing the <i>TAB</i> key:</p>
 <pre>
 $ make me&lt;TAB&gt;