Update cofarming and private testnet

- typo fix in cofarming initial CHI_ROOT export
- update private testnet to include genesis challenge link and improve formatting

docs/getting-started/testnets.md

@@ -97,7 +97,7 @@ Alternatively, you can manually edit the ports in `config.yaml`.
 
 ```bash
 # Export the Chia root
-export CHIA_ROOT ~/.chia/testnet
+export CHIA_ROOT=~/.chia/testnet
 
 # Initialize testnet
 chia init
@@ -151,8 +151,8 @@ To swap between running commands for mainnet and running commands for testnet, y
 
 0. Stop all chia processes. Check that they have stopped with `ps -ef | grep chia`
 1. Create a new chia root using `export CHIA_ROOT="~/.chia/my_testnet"`, then `chia init`. Don't forget to export CHIA_ROOT, or prefix your chia commands with `CHIA_ROOT="~/.chia/my_testnet"` if you want to run on my_testnet when starting a new terminal.
-2. Create a new entry in config.yaml with a different GENESIS_CHALLENGE, and reduced DIFFICULTY_CONSTANT_FACTOR. 2^67 constant factor is around 110PiB assuming a fast timelord. So if you have around 110GiB, you can set it to 2 ^ 47. Decrease SUB_SLOT_ITERS_STARTING to something like 2^23 if you are using a slow computer. Decrease PLOT_FILTER if you want to have more proof checks per signage point. 
-3. Make sure to add **my_testnet** to all places that need it, like network_overrides.config, and selected_network
+2. Create a new entry in config.yaml with a different [GENESIS_CHALLENGE](https://docs.chia.net/consensus-challenges/#genesis-challenge), and reduced `DIFFICULTY_CONSTANT_FACTOR`. `2^67` constant factor is around 110PiB assuming a fast timelord. So if you have around 110GiB, you can set it to `2 ^ 47`. Decrease `SUB_SLOT_ITERS_STARTING` to something like `2^23` if you are using a slow computer. Decrease `PLOT_FILTER` if you want to have more proof checks per signage point. 
+3. Make sure to add **my_testnet** to all places that need it, like `network_overrides.config`, and `selected_network`
 4. Change the introducer URLs to point to localhost so you don't contact the real ones
 5. Do `sh install-timelord.sh`
 6. Run the system with `chia start all`