Update proposer and validator set wording

Co-authored-by: Mário Havel <[email protected]>

docs/wiki/CL/overview.md

@@ -54,7 +54,7 @@ _Time moves from left to right and, except for the Genesis block, each block poi
 </figcaption>
 </figure>
 
-The chain grows as nodes add new blocks to its tip. This is done by temporarily selecting a "leader", the node that extends the chain. In PoW, the leader is the miner who first solves the PoW puzzle for its block. In Ethereum's PoS, the leader is pseudo-randomly selected from active stakers.
+The chain grows as nodes add new blocks to its tip. This is done by temporarily selecting a "leader", the node that extends the chain. In PoW, the leader is the miner who first solves the PoW puzzle for its block. In Ethereum's PoS, the proposer is pseudo-randomly selected from active validator set.
 
 The leader (block proposer) adds a block to the chain, choosing and ordering its contents. The block must be valid according to protocol rules, or the network will ignore it. Using blocks is an optimization. Adding individual transactions one by one would create a huge consensus overhead. So blocks are batches of transactions, and sometimes [people argue](https://www.bitrawr.com/bitcoin-block-size-debate-explained) about how big those blocks should be. The size of these blocks can vary: