Add guide for writing rule types (#351)

* Add comprehensive guide for writing rule types

This commit adds documentation to help developers write custom rule types.

The guide includes:
- Complete rule type anatomy and structure
- Detailed explanations of ingestion, evaluation, and remediation
- Multiple working examples from this repository
- Best practices and common patterns
- Quick reference for syntax and built-in functions

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* Address PR feedback on rule type documentation

- Add link to Open Policy Agent documentation for Rego
- Add guidance about parameter design to avoid overly configurable rules
  that can contradict their security purpose

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

---------

Co-authored-by: Claude <[email protected]>

Author: JAORMX

README.md

@@ -25,14 +25,23 @@ The entity itself, however, always originates from a provider.
 
 ## How to get started with writing rules and profiles?
 
-To get started with writing rules and profiles, you can check the following resources:
+### Quick Start Guides
+
+For comprehensive, repository-specific guides on writing rule types:
+- **[Writing Rule Types: Comprehensive Guide](./docs/writing-rule-types.md)** - In-depth guide with examples and best practices
+- **[Rule Type Quick Reference](./docs/rule-type-quick-reference.md)** - Concise syntax reference for quick lookup
+
+### Official Minder Documentation
+
 - [How to write a rule type](https://mindersec.github.io/how-to/custom-rules)
 - [How to write a rule type using Rego](https://mindersec.github.io/how-to/writing-rules-in-rego)
 - [How to use mindev to develop and debug rule types](https://mindersec.github.io/how-to/mindev)
 - [How to write rules and profiles - YouTube](https://www.youtube.com/watch?v=eXp0nyd72d4)
 - [Minder documentation](https://mindersec.github.io)
 - [Rego language tutorial](https://www.openpolicyagent.org/docs/latest/policy-language/)
 
+### Reference Examples
+
 Apart from that, you can also check the reference rules and profiles in this repository to get an idea of how to write, structure, and organize them.
 
 - Rule types: the reference rule types are available in the `rule-types` directory. To take these rule types