Update testnet.md (#145)

fix broken links

doc/src/testnet/testnet.md

@@ -6,9 +6,9 @@ testnet. In it, we cover basic setup of the `darkfid` node daemon,
 initializing a wallet, and interacting with the _money contract_,
 which provides infrastructure for payments and atomic swaps.
 
-1. [Compile and run a node](testnet/node.md)
-2. [Airdrop yourself funds](testnet/airdrop.md)
-3. [Make some payments](testnet/payment.md)
-4. [Do some atomic swaps](testnet/atomic-swap.md)
-5. [Create an on-chain DAO](testnet/dao.md)
+1. [Compile and run a node](node.md)
+2. [Airdrop yourself funds](airdrop.md)
+3. [Make some payments](payment.md)
+4. [Do some atomic swaps](atomic-swap.md)
+5. [Create an on-chain DAO](dao.md)