Add SDK issue completion self-review template

[El-swaggerito]

Description

Difficulty: Hard

Type: Documentation

Summary

Create a self-review template for SDK contributors before requesting review.

Current Behaviour

Contributors may not objectively check whether their issue is actually complete.

Expected Behaviour

The SDK repo should provide a self-review template covering requirements, tests, CI, documentation, and edge cases.

Suggested Implementation

Create template docs, add PR template reference, and include examples.

Files or Areas Likely Affected

• docs/
• .github/
• README.md

Acceptance Criteria

• Self-review template is added.
• Issue requirements are covered.
• Tests and CI are covered.
• Documentation impact is covered.
• Edge cases are included.
• README links to the template.

Additional Notes

This aligns with the instruction to self-evaluate before payment day.