Add a CONTRIBUTING.md

- added this to fulfill GitHub's community guidelines, because ocd.

CONTRIBUTING.md

@@ -0,0 +1,25 @@
+# Contributing to orbum
+First things first: Thank you for your interest in contributing to orbum!
+
+## Code style guidelines
+* Struct naming: Usually `CamelCase`, but `CamelCase_AdditionalInfo` is acceptable. (examples: `VifUnit` and `GifRegister_Ctrl`)
+* Function/method naming: `snake_case()`
+* Variable/struct members naming: `snake_case` or `snake_case1` or `snake_case_1`.
+* Braces placement: Curly braces should appear on the newline.
+* Indentation: 4-width spaces.
+* Comments: `/// something` or `// something`; mostly similar to the Rustaceans' usage (not strictly enforced, though...)
+
+Note:
+* Put state-tracking variables in Resources (either the unit's Ctrl register or the unit's struct). Controllers should strictly contain logical code only.
+* (Usually you should) Use classes instead of namespaces
+* When in doubt, run clang-format on your files.
+```bash
+    # run this command in the top directory! it is where .clang-format is located.
+    clang-format -i -style=file <path-to-your-files>
+```
+
+## Issue/PR templates
+* Um... I don't think we need it now. Maybe when the emulator starts booting games.
+
+## Code of conduct
+* Uhhhh... just don't spam or annoy people or something, be a nice person. That's it.