misc changes

.env.example

@@ -1,5 +1,3 @@
 PRIVATE_KEY=
 INFURA_KEY=
-ETHERSCAN_API_KEY=
-POLYGONSCAN_API_KEY=
-POLYGONSCAN_ZKEVM_API_KEY=
+ETHERSCAN_API_KEY=

CONTRIBUTING.md

@@ -103,7 +103,7 @@ The repo follows the official [Solidity Style Guide](https://docs.soliditylang.o
   abstract contract AccessControl is ..., {
   ```
 
-- Unchecked arithmetic blocks should contain comments explaining why overflow is guaranteed not to happen. If the reason is immediately apparent from the line above the unchecked block, the comment may be omitted.
+- Unchecked arithmetic blocks should contain comments explaining why overflow is guaranteed not to happen or permissible. If the reason is immediately apparent from the line above the unchecked block, the comment may be omitted.
 
 ### Interfaces
 
@@ -137,16 +137,6 @@ After deployments are executed a script is provided that extracts deployment inf
 
 ### Deployment
 
-This repo set up the following RPCs in the `foundry.toml` file:
-
-- mainnet: Ethereum Mainnet
-- goerli: Ethereum Goerli
-- sepolia: Ethereum Sepolia
-- polygon_pos: Polygon PoS
-- mumbai: Polygon Mumbai
-- polygon_zkevm: Polygon zkEVM
-- polygon_zkevm_testnet: Polygon zkEVM Testnet
-
 To deploy the contracts, provide the `--broadcast` flag to the forge script command. Should the etherscan verification time out, it can be picked up again by replacing the `--broadcast` flag with `--resume`.
 Deploy the contracts to one of the predefined networks by providing the according key with the `--rpc-url` flag. Most of the predefined networks require the `INFURA_KEY` environment variable to be set in the `.env` file.
 Including the `--verify` flag will verify deployed contracts on Etherscan. Define the appropriate environment variable for the Etherscan api key in the `.env` file.