First time setup issues on Windows following optimization recommendations

## Describe the issue

Enhancements for the Windows target in `Getting Started > Setup` are incorrect and lead to failed compiles.

## Proposed Solution

There are three major problems I ran into while troubleshooting this I needed to resolve before getting to a successful build.

1. `sccache` has a bug with the current latest version `0.17.0`

https://github.com/mozilla/sccache/issues/2397

2. nightly `share-generics` advice is backwards (or at least doesn't have a cutout for Windows developers), but it _is_ correct in the example file link

https://github.com/bevyengine/bevy/pull/2016

https://github.com/bevyengine/bevy/blob/b56fc29d3016e641754765244b5ba3f9cc504671/.cargo/config_fast_builds.toml#L134-L158

3. there's an issue with the nightly trait solver that I was informed on Discord should be temporary, but I still wanted to mention here as well

https://github.com/bevyengine/bevy/issues/25511

## Additional Information (optional)

I fixed these by disabling share-generics, setting next-solver to coherence, and installing sccache@0.16.0.

Start in Getting Started > Setup and compare the Windows optimization instructions with the linked .cargo/config_fast_builds.toml example. Check the referenced sccache, share-generics, and nightly trait-solver reports before updating the guidance; done means a Windows newcomer can follow the setup to a successful compile without the listed failures.

Written by the indexing model from the issue text.