Remove extraneous PATH export

[hyperupcall]

Check list

• [x] I have performed a self-review of my code
• [x] I have commented my code in hard-to-understand areas
• [x] I have made corresponding changes to the documentation

Description

This updates the documentation for using forgit as a subcommand of git by removing the use of the export built-in. For all intensive purposes, PATH is already exported. If it weren't, then executing a subprocess (ex. system("bash ...")) would always fail since PATH wouldn't be copied from parent to child. This simplifies the export line accordingly.

Type of change

• [x] Bug fix
• [ ] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [x] bash
  • [x] zsh
  • [x] fish
• OS
  • [x] Linux
  • [x] Mac OS X
  • [ ] Windows
  • [ ] Others:

[cjappl]

Thanks for the contribution!