message: Improve CLI docs
diff: @@ -59,7 +59,7 @@ typechain --target=(ethers|truffle|web3-v1|path-to-custom-target) [glob]
  `./abis/**/*.abi`, `./abis/?(Oasis.abi|OasisHelper.abi)`
  - `--target` - ethers, truffle, web3-v1 or path to your custom target. typechain will try to load package named
  `typechain-target-${target}`, so make sure that desired package is installed.
  -- `--outDir` - put all generated files to a specific dir
  +- `--outDir` (optional) - put all generated files to a specific dir
  TypeChain always will rewrite existing files. You should not commit them. Read more in FAQ section.
  