Extension version upgrade note (#4742)
Extension version upgrade note (#4742)

* Extension version upgrade note

* Use 'action'

* Revise extension fix descriptions

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