* Upgrade to https: serving for JSON, links in docs
Fixes#5480
* Update boards.rst documentation
* Update more documentation http: refs to https:
* Remove obsolete staging info
* Drop obsolete versions from JSON programatically
After the final merge is done on the JSON, strip out any named versions
from the final product.
Removing 1.6.5-* and 2.5.0-beta(1,2,3) for now.
* Remove 2.4.0-rc(0/1) from JSON, too
* Add fix for SoftwareSerial submodule errors to documentation
* Update installing.rst
Replaces and based on #5602Fixes#5583
* Update installing.rst
Remove forgotten section
Add update section for Other OS