Documenting the "advanced" comment attribute (#468)
Documenting the "advanced" comment attribute (#468)

* Documenting advanced comment attribute

* typo

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