doc: FIX GitHub logo in footer

Author: hynekkar

docs/_includes/social-icon.html

@@ -16,5 +16,5 @@
 	{% when "RSS" %}
 		<svg fill="#000000" height="24" viewBox="0 0 24 24" width="24" xmlns="http://www.w3.org/2000/svg"><path d="M0 0h24v24H0z" fill="none"/><circle cx="6.18" cy="17.82" r="2.18"/><path d="M4 4.44v2.83c7.03 0 12.73 5.7 12.73 12.73h2.83c0-8.59-6.97-15.56-15.56-15.56zm0 5.66v2.83c3.9 0 7.07 3.17 7.07 7.07h2.83c0-5.47-4.43-9.9-9.9-9.9z"/></svg>
 	{% when "GitHub" %}
-		<img height="20" width="20" src="./../images/github.png">	
+		<img height="20" width="20" src="https://cesnet.github.io/ipfixprobe/images/github.png">	
 {% endcase %}