should set up ripgrep properly

1. completion:

for zsh completion, we need to update `FPATH`.

```bash
export FPATH=$HOME/tools/ripgrep/complete:$FPATH
```

2. man doc

```
mkdir -p $HOME/tools/ripgrep/doc/man/man1
mv $HOME/tools/ripgrep/doc/rg.1 $HOME/tools/ripgrep/doc/man/man1
```

The `MANPATH` variable needs to updated too:

```bash
export MANPATH=$HOME/tools/ripgrep/doc/man
```