remove --create-key from completion, its only for migrations

If people want to create repos, they should be using `fdroid init`.  This
flag is for very specific cases: migrating old unsigned repos to signed.
It shouldn't be promoted for anything else since there are better tools for
those tasks.

completion/bash-completion

@@ -145,7 +145,7 @@ __complete_install() {
 
 __complete_update() {
 	opts="-c -v -q -b -i -I -e -w"
-	lopts="--create-metadata --create-key --verbose --quiet --buildreport
+	lopts="--create-metadata --verbose --quiet --buildreport
  --interactive --icons --editor --wiki --pretty --clean --delete-unknown
  --nosign --rename-apks --use-date-from-apk"
 	case "${prev}" in