Add "Developer Guide" to documentation.

[gonzolively]

Task Description

Develop a detailed "Developer Guide" that instructs a developer how to write, build, and deploy container-based applications. Should be supplemental to, but much more detailed than the quickstart guide.

[dkouba-atym]

Noting we are missing flashing instructions for the runtime in the docs.

[gonzolively]

Will this not work?

https://docs.project-ocre.org/quickstart/firmware/

[dkouba-atym]

Ah, the confusion comes from this:

• The Ocre runtime readme has a bunch of instructions, but stops short of programming instructions
• The docs link is likely easily skipped in the readme (I would, and just continue with the instructions in the readme itself)