fix: fix silly docs mistake in pyenv init.

-> Currently we get:
```zsh
pyenv init
# Load pyenv automatically by appending
# the following to
# ~/.zprofile (for login shells)
# and ~/.zshrc (for interactive shells) :

export PYENV_ROOT="$HOME/.pyenv"
[[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -zsh)"
```

But it should obviously be `pyenv init - zsh`.

man/man1/pyenv.1

@@ -14,7 +14,7 @@ pyenv lets you easily switch between multiple versions of Python\. It's simple,
 .RS 15
 .nf
 if command -v pyenv 1>/dev/null 2>&1; then\n
-   eval "$(pyenv init -)" \n
+   eval "$(pyenv init - bash)" \n
 fi
 .fi
 .RE