[Documentation]: Transaction Lifecycle section to be updated

[samricotta]

Summary

The overall feeling of this page is a bit disjointed. The role of FinalizeBlock isnt defined clearly. Additionally we could mention the application mempool is also available. I think the whole section may need a whole rewrite e.g.

In order to verify a Tx, full-nodes call CheckTx, which includes both stateless and stateful checks. 
Further validation happens later in the DeliverTx stage. CheckTx goes through several steps, beginning with decoding Tx

The above is a snippet as an example from outdated documentation and mixing of terminologies