Fix broken link to disjoint_sets

doc/incremental_components.html

@@ -43,7 +43,7 @@ <H1>Incremental Connected Components</H1>
 hence it is called <b><i>incremental</i></b><a
 href="bibliography.html#eppstein97:dynamic_graph">[42]</a> (and not
 fully dynamic). The disjoint-sets class is described in Section <A
-HREF="../../disjoint_sets/disjoint_sets.html">Disjoint Sets</A>.
+HREF="disjoint_sets.html">Disjoint Sets</A>.
 
 <P>
 The following five operations are the primary functions that you will