Add git-tree
Add git-tree

- https://github.com/dehlen/git-tree-zsh/issues/1 is closed, add
`git-tree` plugin.
- Upgrade some `fzf` references to links to [fzf](https://github.com/junegunn/fzf)

Signed-off-by: Joe Block <13bb081c6ac072ef78a3e348068e2204400d7335@unixorn.net>

unixorn/awesome-zsh-plugins,voronkovich/awesome-zsh-plugins