Add zsh(1) completion system configuration for Slic3r.

utils/zsh/README.markdown

@@ -0,0 +1,21 @@
+# ZSH Completions for Slic3r
+
+To enable zsh(1) completions for Slic3r, add the following to your
+``~/.zshrc`` file, replacing ``/path/to/Slic3r/`` with the actual path
+to your Slic3r directory:
+
+    typeset -U fpath
+
+    if [[ -d /path/to/Slic3r/utils/zsh/functions ]]; then
+        fpath=(/path/to/Slic3r/utils/zsh/functions $fpath)
+    fi
+
+    autoload -Uz compinit
+    compinit
+    zstyle ':completion:*' verbose true
+    zstyle ':completion:*:descriptions' format '%B%d%b'
+    zstyle ':completion:*:messages' format '%d'
+    zstyle ':completion:*:warnings' format 'No matches for %d'
+    zstyle ':completion:*' group-name '%d'
+
+See the zshcompsys(1) man page for further details.