updated string docs
updated string docs

Microsoft/pxt,playi/pxt,switch-education/pxt,playi/pxt,switch-education/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,playi/pxt,switchinnovations/pxt,switchinnovations/pxt,Microsoft/pxt,playi/pxt,switchinnovations/pxt,switchinnovations/pxt