Add ZSH autocompletion

Author: yankeexe

README.md

@@ -18,13 +18,31 @@ Copy the executable to any directory in your `$PATH`
 $ sudo cp wt /usr/local/bin
 ```
 
-### Tab Completion
-:warning: Only **bash** completion is available for now.
+### Tab Autocompletion :zap:
 
+**For Bash**
 ```bash
-sudo cp wt_completion /etc/bash_completion.d
+sudo cp completions/wt_completion /etc/bash_completion.d
 ```
 
+**For ZSH**
+> Note: completion file for zsh has `_` prefix
+
+
+Find paths where you can store your completion
+```bash
+print -rl -- $fpath
+```
+
+Copy completion script to one of that location and restart the shell.
+
+```bash
+sudo cp completions/_wt_completion <one-of-$fpath>
+
+exec zsh
+```
+---
+Tab autocompletion works for switching between your worktrees.
 ```bash
 wt <TAB> <TAB>
 

completions/_wt_completion

@@ -0,0 +1,16 @@
+#compdef wt
+
+# AUTOCOMPLETION FOR ZSH
+
+list="$(wt list | awk '{ print $1; }' | tr "\n" " ")"
+declare -A opts
+
+setopt shwordsplit
+for item in $list
+do
+    base="$(basename ${item} | xargs)"
+    opts+=(["$base"]="$base")
+done
+unsetopt shwordsplit
+
+compadd -Qa opts

wt_completion completions/wt_completionwt_completion renamed to completions/wt_completion

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+# AUTOCOMPLETION FOR BASH
+
 _wt() {
     local cur opts
     COMPREPLY=()