remove old files/migrate content

[jaxxzer]

we have some dangling files in the ./software directory after https://github.com/bluerobotics/ardusub-gitbook/pull/135

migrate any needed content to existing pages and remove the files

[Williangalvani]

~http://www.ardusub.com/operators-manual/software-update.html~ is dangling.

We should probably manually edit the pages to add a redirect to the correct place.

[patrickelectric]

• [ ] http://www.ardusub.com/getting-started/initial-setup.html