docs(config): add check_update and display_hyperlinks

Description

Adds the following to glab config --help

- check_update: if true, notifies of any available updates to glab, defaults to false
- display_hyperlinks: if true, and using a TTY, outputs hyperlinks for issues and MR lists, defaults to false

Related Issues

#3703 (comment 1543387135)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap