Add an easy way to jump to the lnk repo

[scratchmex]

This adds a lnk home to print the lnk repo path and documents a shell wrapper so lnk cd takes you there

$ go run ./ -h
...
Available Commands:
...
home        🏠 Print your lnk home path
...

$ go run ./ home -h
Print the lnk repository directory (LNK_HOME, XDG_CONFIG_HOME/lnk, or ~/.config/lnk).

Usage:
  lnk home [flags]

Flags:
  -h, --help   help for home

Global Flags:
      --colors string   when to use colors (auto, always, never) (default "auto")
      --emoji           enable emoji in output (default true)
      --no-emoji        disable emoji in output
  -q, --quiet           suppress all output (exit code only)

closes #51