Add OpenBT to software page

[jared321]

Pending Tasks

• See if a "square" version of the logo exists that would hopefully work better for this application

PR Self-review

• Reviewed changes
• Checked that URLs are correct
  • For SDK, I sensibly get a missing page error. But, with main -> develop, I find the SDK
• Checked that relative paths are correct

The OpenBT SDK is being brought into the develop branch of the bandframework repository in a different PR. It should be included in main as part of the BAND v1 release.

[DanielRPhillips]

I think this is a good & useful website update.

I note that other pieces of software that are being added to BAND for v1.0 are not yet reflected on this page. However, I think there is a rationale for treating OpenBT differently, in that those pieces of software need to themselves be tested, whereas OpenBT is a battle-hardened software tool that is merely being brought into the BAND framework.