Fix misleading Context.Bind documentation comment

[vishr]

Summary

Addresses issue #2382 by correcting the misleading comment on Context.Bind that did not accurately describe the actual binding behavior.

Problem

The comment on Context.Bind in context.go was incomplete and confusing:

Previous comment:

// Bind binds path params, query params and the request body into provided type `i`. The default binder
// binds body based on Content-Type header.

Issues with the old comment:

1. ❌ Didn't explain the binding order (path → query → body)
2. ❌ Didn't mention that later steps can override earlier values
3. ❌ Didn't specify that query params are only bound for GET/DELETE/HEAD
4. ❌ Didn't reference single-source binding methods for more control

Solution

New accurate comment:

// Bind binds data from multiple sources to the provided type `i` in this order:
// 1) path parameters, 2) query parameters (for GET/DELETE/HEAD only), 3) request body.
// Each step can override values from the previous step. For single source binding use
// BindPathParams, BindQueryParams, BindHeaders, or BindBody directly.
// The default binder handles body based on Content-Type header.

Improvements:

• ✅ Clear binding order: Explicitly states the 1-2-3 sequence
• ✅ Override behavior: Warns that later steps can override earlier values
• ✅ HTTP method specifics: Notes query param binding only for GET/DELETE/HEAD
• ✅ Alternative methods: References single-source binding methods
• ✅ Content-Type info: Preserves useful body binding information

Impact

This fix prevents confusion for developers who might expect different behavior from Context.Bind() based on the previous misleading documentation. Now the comment accurately reflects the actual implementation in bind.go.

Type of Change

• 📚 Documentation fix - No code logic changes
• 🔧 Comment improvement - Better developer experience
• 🎯 Issue resolution - Directly addresses reported confusion

Testing

• ✅ Code compiles without issues
• ✅ No functional changes - documentation only
• ✅ Comment aligns with actual DefaultBinder.Bind implementation

Fixes #2382

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This is a simple documentation improvement that enhances clarity for Echo developers using the binding functionality.