FluxML
Revamp `basic.md` (put it under the `getting_started` section)
This PR revamps basic.md and renames it to "Neural Networks from scratch". Most of the content is intact, but I have cleaned up the code and removed the bits and pieces which are not supposed to be used now.
Note: This PR contains the changes from the linear regression PR and the logistic regression PR (without some of these changes, the tests would fail). This PR should be merged after both of these PRs. I will make sure to sync the changes before this PR is merged.
Lastly, I am not sure if this guide should contain a training section. The title talks only about constructing Neural Networks, but I can add a training function and showcase Optimisers.jl.
Rendered guide - https://github.com/Saransh-cpp/Flux.jl/blob/revamp-basic/docs/src/getting_started/neural_nets_from_scratch.md
PR Checklist
- [ ] Tests are added
- [ ] Entry in NEWS.md
- [ ] Documentation, if applicable
