docs: Update docker-machine version

⚠️ ️NOTE THAT THIS FORK IS MAINTAINED FOR CRITICAL BUG FIXES AFFECTING RUNNING COSTS ONLY. NO OTHER CONTRIBUTIONS WILL BE ACCEPTED. ⚠️

What critical bug this MR is fixing?

The documentation was mentioning a VERY outdated version, updated the version mentioned.

How does this change help reduce cost of usage? What scale of cost reduction is it?

None (0).

In what scenarios is this change usable with GitLab Runner's docker+machine executor?