De-emphasize modules

[Frijol]

Discussed today with @tcr and @HipsterBrown.

Problems identified:

• In workshops, users don't get past the modules to discover all of the great networking capabilities
• We are sandboxing people if they don't realize they don't have to use our modules
• USB modules should probably be called out as different from tenpin
• J5IK should be mentioned per https://github.com/tessel/t2-start/issues/133

Ideas:

• Move tenpin modules to the end of the tutorial
• Move tenpin modules to t2-docs (possibly more appropriate anyway) and just reference them from the tutorial, same as current mention of community modules
• Change the "modules" page to a "ports" page which mentions both modules and GPIO uses (and J5IK)
• Separate page for USB talking about how USB devices can interface with Tessel
• Images of the T2 board highlighting which physical piece of the board we're discussing in a given page

cc @rwaldron @reconbot

[Frijol]

@tcr made this exploratory version of t2-docs for the accelerometer module https://github.com/tessel/t2-docs/blob/tcr-modules/Modules/Accelerometer.md

[Frijol]

Put some more thought into this, and I'm now in favor of keeping the module pages in t2-start. The experiences we have there are explicitly first-run. Meanwhile, there do exist separate docs for the modules already, just on their specific module pages. I think it's appropriate for the module first-runs to link out to those, as they already do.

I think the documentation issue regarding modules is better solved by examining how we can best link module documentation and examples from tessel.io/docs through from the Readmes on the repos of those modules. This, while maintaining simple gitbook format, but also keeping the readmes where they are because that's good documentation for npm.

^ none of which solves the central point of this issue :)