chore(contract-docs): update

Author: Yurii721

docs/Counter.md

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+# Solidity API
+
+## Counter
+
+### constructor
+
+```solidity
+constructor() public
+```
+
+### x
+
+```solidity
+uint256 x
+```
+
+### Increment
+
+```solidity
+event Increment(uint256 by)
+```
+
+### inc
+
+```solidity
+function inc() public
+```
+
+### incBy
+
+```solidity
+function incBy(uint256 by) public
+```
+

docs/Lock.md

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+# Solidity API
+
+## Lock
+
+### unlockTime
+
+```solidity
+uint256 unlockTime
+```
+
+### owner
+
+```solidity
+address payable owner
+```
+
+### Withdrawal
+
+```solidity
+event Withdrawal(uint256 amount, uint256 when)
+```
+
+### constructor
+
+```solidity
+constructor(uint256 _unlockTime) public payable
+```
+
+### withdraw
+
+```solidity
+function withdraw() public
+```
+