updated readme (#27)

Author: adarshaks91

README.md

@@ -4,6 +4,36 @@
 
 While the Content and Structure is defined in the [Methodology Taxonomy](https://github.com/bugcrowd/methodology-taxonomy), this defines methods to allow for easy handling of methodologies logic.  This gem is used and maintained by [Bugcrowd Engineering](https://bugcrowd.com).
 
+## Submodule Versioning Strategy
+
+This gem uses a **versioned submodule approach** to ensure backward compatibility and prevent breaking changes (like step not found or empty checklist title or description) in active pentest engagements when a hacker tries to complete a methodology:
+
+### How It Works
+- Each gem version should have a corresponding submodule directory in `lib/data/`
+- When methodology-taxonomy is updated, a new submodule directory should be created matching the gem version
+- Existing pentest engagements continue using their original methodology version
+- New pentest engagements can use the latest methodologies when a hacker tries to complete those methodologies
+
+### Example Structure
+```
+lib/data/
+├── 0.1/    # Legacy methodologies
+├── 0.9/    # Previous version methodologies  
+├── 1.0/    # Current version methodologies
+└── 1.1/    # Latest version methodologies
+```
+
+### Why This Matters
+- **Prevents Breaking Changes**: Step keys, item keys, and methodology structure changes won't break existing pentest engagements in CrowdControl
+- **Maintains Backward Compatibility**: Hacker can complete the methodology for a pentest engagement using the methodology version they started with
+- **Enables Updates**: New pentest engagements benefit from the latest methodology improvements/updates
+
+### Versioning Pattern
+- **Major/Minor versions** get their own submodule directory (e.g., `0.1/`, `0.9/`, `1.0/`)
+- **Patch versions** within the same minor version share the same submodule directory
+- **Latest directory** contains the most recent methodology updates
+- **Legacy directories** are maintained for backward compatibility with existing engagements
+
 ## Installation
 
 Add this line to your application's Gemfile: