Adds a second addendum addressing the block activation heights for release 2.4.
Accepted text is not changed; this PR adds a another section specifying that the activation will happen prior to cycle 60 and specifies the block height at which activation will occur.
The second hard fork will take effect 400 Bitcoin blocks prior to the start of the prepare phase for cycle #60, which is Bitcoin block height 791551.
Adds a second addendum addressing the block activation heights for release 2.4. Accepted text is not changed; this PR adds a another section specifying that the activation will happen prior to cycle 60 and specifies the block height at which activation will occur.