Introduce Mod Integration section

[sleepy-evelyn]

Introducing a section on mod integration. Will link to #53 once merged as there is a mention of the mod metadata.

Currently WIP. The Location of files and links to other articles may be adjusted depending on whether recent PRs are merged. Especially #53 and #52.

the Integration section will get split into 3 separate pages.

Basic Concepts

• Basic Introduction
• Conditional execution depending on if certain mods are installed
• Discussion of shared registries. Lucky Ducks example included

API usage and development

• Using Mod APIs. Use EMI example.
• API tips, tricks and best practices (seperate page)
• Integration with a full mod loaded within gradle.

The Danger Zone

• Inter-mod Mixin injection example
• Inter-mod class location and retrieval

[sylv256]

Possible to-do: mention how to add compatibility with other mods via the QMJ (e.g. modmenu)