Update usage.md

Author: hiddewie

docs/usage.md

@@ -129,7 +129,7 @@ should give the same rows as no hstore, just with the additional hstore column.
 
 Hstore is used to give more flexibility in using additional tags without
 reimporting the database, at the cost of a
-[less speed and more space.](http://paulnorman.ca/blog/2014/03/osm2pgsql-and-hstore/)
+[less speed and more space.](http://www.paulnorman.ca/blog/2014/03/osm2pgsql-and-hstore/)
 
 ## Projection options
 
@@ -142,7 +142,7 @@ reimporting the database, at the cost of a
 
 * `--multi-geometry` skips an optimization for rendering where PostGIS
   MULTIPOLYGONs are split into multiple POLYGONs. `--multi-geometry` can be
-  used to [avoid some labeling issues at the cost of speed](http://www.paulnorman.ca/blog/2014/03/osm2pgsql-and-hstore/).
+  used to [avoid some labeling issues at the cost of speed](http://www.paulnorman.ca/blog/2014/03/osm2pgsql-multipolygons/).
   It is also typically required for [analysis](analysis.md).
 
 * `--keep-coastlines` disables a hard-coded rule that would otherwise