Correct keyblock() type

src/hz.erl

@@ -125,13 +125,14 @@
 %   "info"          => contract_byte_array(),
 %   "miner"         => account_id(),
 %   "nonce"         => non_neg_integer(),
-%   "pow"           => [non_neg_integer()],
 %   "prev_hash"     => microblock_hash(),
 %   "prev_key_hash" => keyblock_hash(),
+%   "seal"          => #{"data" => [int()],
+%                        "signature" => signature()}
 %   "state_hash"    => block_state_hash(),
 %   "target"        => non_neg_integer(),
 %   "time"          => non_neg_integer(),
-%   "version"       => 5}.
+%   "version"       => 1}.
 % </pre>
 -type microblock_header()   :: #{string() => term()}.
 % <pre>
@@ -353,7 +354,7 @@ top_height() ->
 
 
 -spec top_block() -> {ok, TopBlock} | {error, Reason}
-    when TopBlock :: microblock_header(),
+    when TopBlock :: microblock_header() | keyblock(),
          Reason   :: chain_error().
 %% @doc
 %% Returns the header of the current top block.