Fix README (#5)

README.md

@@ -4,6 +4,11 @@ Repository holding the contracts made by Gnosis Labs team.
 
 ## Implemented contracts
 
+| Contract Name             | Description                                           | Mainnet Address                           |
+|----------------------------|-------------------------------------------------------|-------------------------------------------|
+| OmenThumbnailMapping     | Manages IPFS hashes for market thumbnails on Omen 2.0 | [0xe0cf08311F03850497B0ed6A2cf067f1750C3eFc](https://gnosisscan.io/address/0xe0cf08311f03850497b0ed6a2cf067f1750c3efc#code)   |
+
+
 ### Omen ThumbnailMapping
 
 Contract used to store prediction market's address to IPFS hash of an image displayed on Omen 2.0
@@ -71,7 +76,7 @@ forge create --gas-limit 10000000 --rpc-url https://rpc.chiadochain.net  --priva
 #### On MainNet
 
 ```shell
-ETHERSCAN_API_KEY=<your_api_key> forge create --verify --verifier-url api.gnosisscan.io --rpc-url https://gnosis-rpc.publicnode.com --private-key <your_private_key> OmenThumbnailMapping
+ETHERSCAN_API_KEY=<your_api_key> forge create --verify --verifier-url https://api.gnosisscan.io/api --rpc-url https://gnosis-rpc.publicnode.com --private-key <your_private_key> OmenThumbnailMapping
 ```
 
 ### Cast