update execute html to use <code> tag
-<pre data-execute="r"># No inputs, no output</pre>
-<pre data-execute="r" data-input="var1"># One input, no output</pre>
-<pre data-execute="r" data-input="var1,var2"># Two inputs, no output</pre>
-<pre data-execute="r" data-output="out" data-input="var1,var2"># Two inputs, an output</pre>
-<pre data-execute="r" data-output="out"># No input, an output</pre>
-<pre data-execute="r" data-output="out" data-input="var1,var2" data-width="3cm" data-show="true"># Inputs, output and options</pre>
+<pre data-execute="r"><code># No inputs, no output</code></pre>
+<pre data-execute="r" data-input="var1"><code># One input, no output</code></pre>
+<pre data-execute="r" data-input="var1,var2"><code># Two inputs, no output</code></pre>
+<pre data-execute="r" data-output="out" data-input="var1,var2"><code># Two inputs, an output</code></pre>
+<pre data-execute="r" data-output="out"><code># No input, an output</code></pre>
+<pre data-execute="r" data-output="out" data-input="var1,var2" data-width="3cm" data-show="true"><code># Inputs, output and options</code></pre>
<pre class="r"><code># Just a codeblock</code></pre>
\ No newline at end of file
