Typo fixed.

docs/getting-started.html

@@ -80,7 +80,7 @@
 			<p class="section-content">
 			<p>Command line:</p>
 			<pre><code>
-	https://github.com/marcobambini/gravity.git
+	git clone https://github.com/marcobambini/gravity.git
 	cd gravity
 	make
 			</code></pre>