fix documentation build, misc bugs and add doctests

[Fe-r-oz]

This PR aims to fix documentation build, misc bugs and add doctests.

[Fe-r-oz]

@esabo, The PR is ready review, Thank you!

P.S. Added more doctests as well.

[esabo]

So I guess one question is whether or not we want to move these doc tests to tutorials or actual docs and out of the doc strings themselves?

[Fe-r-oz]

I think tutorials require documentation about the code itself as well as seen from other tutorials. I think we can have docstrings in the tutorial as well once we write about weight reduction for example. There seems to be a bug, I have reported it to HQ.

I think even MethodTypingSignature didn't removed the warnings:

 │  ┌ Warning: Unable to install the GAP packages LINS.
│  └ @ CodingTheory ~/work/CodingTheory/CodingTheory/src/CodingTheory.jl:41
│  ┌ Warning: Replacing docs for `CodingTheory.weight_plot :: Union{}` in module `CodingTheory`
│  └ @ Base.Docs docs/Docs.jl:243

Documentation build passes now most of the time, as seen from actions, it's the build runner CI sometime didn't run so the error this time.

[esabo]

I'd like to get this pulled in. What's the status of this?

[Fe-r-oz]

LGTM as documentation build passes.