fix description of current_block_hash and current_block_num in SYNC_STATUS

[ShahakShama]

This change is 

[ArielElp]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @EvyatarO and @ShahakShama)

---

api/starknet_api_openrpc.json line 1075 at r1 (raw file):

                    "current_block_hash": {
                        "title": "Current block hash",
                        "description": "The hash of the most advanced block that's synchronized",

latest block up to which the node is fully synchronized (same below)