docs: Add related community resources section

[XelaNull]

Hi @Dukefarming! 👋

I came across your FS25-lua-scripting repo while researching resources for FS25 modding. Having the raw Lua source from the dataS folder available (267 files!) is incredibly helpful - especially for understanding how Giants implements things internally. Thanks for putting this together!

I've been working on a complementary resource called the FS25 AI Coding Reference as part of my UsedPlus mod development. It focuses on battle-tested implementation patterns and common pitfalls - the "how do I actually build X?" questions that come up during modding.

What the AI Coding Reference includes:

Metric	Value
Documentation Files	27
Lines of Documentation	9,334
Validated Patterns	70+
Pitfalls Documented	17
Source Mods Analyzed	164+

Topics covered:

• GUI dialog patterns (MessageDialog, XML structure, coordinate system)
• Network events for multiplayer sync
• Manager singletons with save/load integration
• Shop UI customization
• Extensions/hooks for game classes
• Vehicle configurations & specializations
• Triggers, animations, placeables
• And a dedicated "What Doesn't Work" pitfalls guide

I also discovered @umbraprior's FS25 Community LUADOC which has comprehensive API documentation (1,661 pages covering 11,102 functions!).

Together, these three resources form something of a trifecta for FS25 modders:

• Your repo → Raw source (how Giants implements things internally)
• Community LUADOC → API reference (function signatures, parameters, returns)
• AI Coding Reference → Implementation patterns (working examples, pitfalls)

I've already added links to both your repo and umbraprior's in my documentation: see here

This PR simply adds a small "Related Community Resources" section to your README with links to the other two resources. I'm not asking for prominent placement - just a small mention so modders can discover all three. Feel free to adjust the placement or wording however you'd like!

I'm also reaching out to umbraprior with a similar PR.

Thanks for your contribution to the FS25 modding community! 🚜