Move reindexing step.

specification/hugr.md

@@ -1261,11 +1261,11 @@ The new hugr is then derived as follows:
     For each child $C$ of $P$ (in order), if $C \in S$, redirect the hierarchy edge $P \rightarrow C$ to
     target the next node in $N$. Stop if there are no more nodes in $N$.
     Add any remaining nodes in $N$ to the end of $P$'s list of children.
-    (Reindexing may be necessary after this step.)
 6.  For each node $(n, b = B(n))$ and for each child $m$ of $b$, replace the
     hierarchy edge from $b$ to $m$ with a hierarchy edge from the new copy of
     $n$ to $m$ (preserving the order).
-7.  Remove all nodes in $R$ and edges adjoining them.
+7.  Remove all nodes in $R$ and edges adjoining them. (Reindexing may be
+    necessary after this step.)
 
 ##### Outlining methods