added snippet for else (since we already have if/endif)

UltiSnips/jinja.snippets

@@ -4,6 +4,10 @@ snippet if	"If block" i
 {% endif %}
 endsnippet
 
+snippet else "Else"
+{% else %}
+endsnippet
+
 snippet for "For loop"
 {% for ${1:variable} in ${2:set} %}
 	$0