docs: Add configuration option for Fish 3.2.0+ (#2449)
docs: Add configuration option for Fish 3.2.0+ (#2449)

The original instructions were added 2 years ago in https://github.com/pyenv/pyenv/commit/0f2d659732094f6bef11361dbc6261132edc63e2. Since then, [Fish released](https://github.com/fish-shell/fish-shell/releases/tag/3.2.0) [a more declarative instruction for this operation](https://fishshell.com/docs/current/cmds/fish_add_path.html), which is now the recommended way of manipulating `PATH` in Fish.
pyenv/pyenv,pyenv/pyenv,pyenv/pyenv