join current path with given path
```shell
pwd /Users/ashigirl96/.ghq/src/github.com/ashigirl96/pwdf pwdf /Users/ashigirl96/.ghq/src/github.com/ashigirl96/pwdf ```
```shell
pwdf ../pwdf/Cargo.lock /Users/ashigirl96/.ghq/src/github.com/ashigirl96/pwdf/Cargo.lock ```