message: DOC: Fix readme syntax
diff: @@ -31,6 +31,7 @@ Recent Changes
  - New algorithm by @jmcomets: A* search algorithm in ``petgraph::algo::astar``
  - One ``StableGraph`` bug fix whose patch was supposed to be in the previous
  version:
  +
  + ``add_edge(m, n, _)`` now properly always panics if nodes m or n don't
  exist in the graph.
  