Update cli.md (#2239)
Update cli.md (#2239)

Added missing dependency install instructions for Windows users.
Microsoft/pxt,switchinnovations/pxt,playi/pxt,switchinnovations/pxt,Microsoft/pxt,Microsoft/pxt,switch-education/pxt,switchinnovations/pxt,switchinnovations/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,playi/pxt,playi/pxt,switch-education/pxt,switch-education/pxt