ELI15: Gadgets Blank in User Documentation

[gumdropsteve]

Which section of the Halo 2 book were you reading?

I was reading gadgets.md from the /user section which can be found halo2/blob/main/book/src/user/gadgets.md or online.

What was unclear?

There is no content in the # Gadgets section, none was ever pushed.

zcash/halo2/blob/main/book/src/user/gadgets.md is blank and displays blank online as expected.

What would help to make it clearer to you?

Given the file has not been edited in 4 years, I am interested to know if this was/is a planned/active module that was never documented or an error that has not been cleaned.

The file should either be removed or updated.

Naming could also be made consistent. This is in the User-Documentation section in the hosted docs and in the /user/ section in the code.