CSharp Module tweak & Unity Tutorial part 1, 2b, 3 tweaks

[Lethalchip]

Small tweaks to CSharp module index.md:

• Added .Tag property to docs
• Revised example usage for both Is* usage and .Tag usage
• Fixed "Two" to "Four" in special reducer section
• Added examples for each [SpacetimeDB.Reducer(ReducerKind.XXX)]

Small tweak in Unity tutorial part-1.md:

• Fixed hyperlinks to Rust CSharp part-2

Fixed typos and mistakes throughout part-2b-c-sharp.md:

• Changed Identity to uint in Config table
• Updated Throw typo to throw
• Updated logging to correctly use $""
• Fixed [SpacetimeDB.Reducer(ReducerKind.Connect)] typo (it said Init before)
• Removed extraneous publish block, as there was already one at the end
• Fixed UpdatePlayerLoginState() error by switching private to public for compile

Fixed typos and clarified filenames in first-half of part-3.md:

• Renamed GameManager.cs throughout to BitcraftMiniGameManager.cs
• Added path clarifications to various filenames throughout
• Fixed typos on PlayerComponent.FilterByOwnerId => PlayerComponent.FilterByIdentity instead
• Removed .FirstOrDefault();'s from UIUsernameChooser.cs as not needed
• Corrected .Text to .text on UIUsernameChooser.cs

My changes stop at around the **Append to bottom of RemotePlayer class in RemotePlayer.cs:** - L230.

The tutorial, or the code files provided are completely outdated and cannot be followed. I noticed that @dylanh724 has a PR #37 which likely fixes these issues, and probably some of the issues I fixed above.

Anyway, I figured that I would provide my tweaks in case they are helpful to you, no worries either way.

[RReverser]

Other than the outdated sections due to the new breaking API changes, this looks good, thanks!