Fix ECDSA broken node links. Reported by Nick Alcock.

ed87a20a · Niels Möller · bc74431c · ed87a20a
Commit ed87a20a authored Sep 19, 2016 by Niels Möller
--- a/nettle.texinfo
+++ b/nettle.texinfo
@@ -4217,7 +4217,7 @@ accesses depend only on the size of the input data and its location in
 memory, not on the actual data bits. This implies a performance penalty
 in several of the building blocks.

-@node ECDSA, Side-channel silence, Curve 25519, Elliptic curves
+@node ECDSA, Curve 25519, Side-channel silence, Elliptic curves
 @comment  node-name,  next,  previous,  up
 @subsubsection ECDSA