docs: broken links (#4557)

### Description

Some of the links in
[solidity/contracts/middleware/README.md](https://github.com/hyperlane-xyz/hyperlane-monorepo/blob/main/solidity/contracts/middleware/README.md)
were linked to invalid URLs. I updated those links to the correct
addresses and replaced them.

solidity/contracts/middleware/README.md

@@ -3,13 +3,13 @@
 ## Interchain Accounts
 
 An interchain account is a smart contract that is deployed on a remote chain controlled exclusively by the origin chain's deployer account.
-Interchain accounts provide developers with a [transparent multicall API](../OwnableMulticall.sol) to remote smart contracts.
+Interchain accounts provide developers with a [transparent multicall API](libs/OwnableMulticall.sol) to remote smart contracts.
 This avoids the need to deploy application specific smart contracts on remote chains while simultaneously enabling cross-chain composability.
 
 See [IBC Interchain Accounts](https://github.com/cosmos/ibc/blob/main/spec/app/ics-027-interchain-accounts/README.md) for the Cosmos ecosystem equivalent.
 
 ## Interchain Query System
 
-The interchain query system generalizes view calls to contracts on remote chains. It is a [transparent multicall API](../OwnableMulticall.sol) that can be used to query remote smart contracts. This avoids the need to deploy application specific smart contracts on remote chains while simultaneously enabling cross-chain composability.
+The interchain query system generalizes view calls to contracts on remote chains. It is a [transparent multicall API](libs/OwnableMulticall.sol) that can be used to query remote smart contracts. This avoids the need to deploy application specific smart contracts on remote chains while simultaneously enabling cross-chain composability.
 
 See [IBC Interchain Query System](https://github.com/cosmos/ibc/tree/main/spec/app/ics-031-crosschain-queries) for the Cosmos ecosystem equivalent.