Port some of the documents and programs from barefootnetworks/Open-Tofino

[fruffy]

Maybe we can add the documentation and some of the tooling available in https://github.com/barefootnetworks/Open-Tofino to this repository. Although I suspect most of this is redundant.

[vgurevich]

The only file that we really need is PUBLIC_Tofino-Native-Arch.pdf.

The (more) recent versions of the rest can be found in this repo.

There are no tools in that repo. There is a separate private repo that is used to create the files in Open-Tofino by copying filed from the SDE and replacing/adding the license, but I do not think it makes sense anymore.

On the other hand, you can take a look at https://github.com/p4ica/tools that does contain many useful tools for Tofino programming. I know that there is not much documentation there (it is mostly spread across the academy materials), but this can be added, especially if there is some help.

[jafingerhut]

Having a doc directory in this repo, with one article linking to other useful repositories, seems like an excellent idea. Linking to the PUBLIC_Tofino-Native-Arch.pdf from this one seems nearly as convenient to users as copying that file into this repo, but I'm fine either way.