update link to ucp science experiments page (#6766)

fix note indexing (#6765)

Improve/fix melody string parsing (#6762)

Extension: add KY-040 Rotary Encoder Plus (#6753)

Releasing 8.0.21 to live (#6755)

[pxt-cli] bump version to v8.1.10 (#6757)

bump pxt-core to 12.3.5 (#6756)

set and explain the 'Show data' console button (#6736)

Compass docs update (#6728)

use a block config to set the 'for' loop to 3 (#6733)

Update electronManifest version to v8.0.19 (#6725)

sync the hints in 'snap the dot' tutorials (#6727)

set sound threshold to 128 in hints (#6726)

page revisions for default group id (#6715)

add a task to set the group ID (#6717)