bootloaders.json - remove trailing commas & add 82 boards

[durapensa]

Tested locally, makes mcufamily search/filter inclusive all 234 boards displayed.

Note, removing trailing commas was required for Python's JSON module to not barf on loading the file (the revised bootloaders.json was generated from a python script, so there are a few alphabetical reorders & other json cleanups too). Jekyll seems happy either way.

[FoamyGuy]

Looks good to me.

I tested the changes locally and verified a handful full of devices still show proper bootloader information on their downloads page.

Thanks for this cleanup and the additions @durapensa

[dhalbert]

Thank you!

I pushed another commit which cleaned up the bootloader doc a bit. There was some redundant text and I also normalized the formatting.

I re-tested with local builds and also verified the HTML to make sure the tags matched up.