Unofficial-list-of-3rd-party-boards-support-urls please add link

[jpnielsen]

https://github.com/arduino/Arduino/wiki/Unofficial-list-of-3rd-party-boards-support-urls

please add:

Raspberry Pi Pico Arduino core, for all RP2040 boards
https://github.com/earlephilhower/arduino-pico/

https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

[per1234]

Thanks @jpnielsen. I have added it:
https://github.com/arduino/Arduino/wiki/Unofficial-list-of-3rd-party-boards-support-urls/_compare/fcb3865b319111fe82da82c250b3301ea15603f8...4eb7cf856c9b36fcbb1d77a55a6cafee9e7848ac

I have also restored the public editing permissions to the wiki so everyone will once again be able to contribute to it. There was some malicious activity in the wiki and so I temporarily disabled editing.