Add improved completion.zsh script for fastlane

Tweaked in order to also support lanes defined in `fastlane/lanes/*.rb`

Author: AliSoftware

fastlane/completion.zsh

@@ -0,0 +1,36 @@
+#!/bin/zsh
+
+# This is a revised version of the ZSH completion script for fastlane
+# which adds support for some lanes being defined in `fastlane/lanes/*.rb`
+#
+# Based on https://github.com/fastlane/fastlane/blob/master/fastlane/lib/assets/completions/completion.zsh
+#
+# To install, copy this file to `~/.fastlane/completions/completion.zsh`,
+# then `source` it from your `~/.zshrc`.
+#
+_fastlane_complete() {
+  local word completions file
+  word="$1"
+
+  # look for Fastfile either in this directory or fastlane/ then grab the lane names
+  if [[ -e "Fastfile" ]] then
+    file=("Fastfile")
+  elif [[ -e "fastlane/Fastfile" ]] then
+    file=("fastlane/Fastfile")
+  elif [[ -e ".fastlane/Fastfile" ]] then
+    file=(".fastlane/Fastfile")
+  else
+    return 1
+  fi
+
+  # Add any fastlane/lanes/*.rb file too, if any
+  files=("$file" fastlane/lanes/*.rb(N))
+
+  # parse 'beta' out of 'lane :beta do', etc
+  completions="$(sed -En 's/^[ 	]*lane +:([^ 	]+).*$/\1/p' "${files[@]}")"
+  completions="$completions update_fastlane"
+
+  reply=( "${=completions}" )
+}
+
+compctl -K _fastlane_complete bundle exec fastlane