Update blockchain.md
please add this paragraph at the end of consensus section.
@@ -63,6 +63,10 @@ their stake to be elected to create a block. Each lottery draw is private to
each stake pool, so that the overall network doesn't know in advance who can
or cannot create blocks.
+In Genesis-Praos slot time duration is constant, however the frequency of
+creating blocks is not stable, since the creation of blocks is a probability
+that is linked to the stake and active slot coefficient.
+
## Leadership
The leadership represent in abstract term, who are the overall leaders of the
