Documentation: Add Comprehensive Documentation for SDK and Webhook Usage

[shiningflash]

Changes Included

• Enhanced readme.md with project overview, setup guide, and usage details.
• Added docs/sdk_usage.md with a detailed guide for SDK usage.
• Added docs/webhook_guide.md with a comprehensive guide for webhook functionality.

Why These Changes?

• To provide developers with clear, robust, and user-friendly documentation.
• Align the project with best practices for documentation and usability.

How to Review

• Review readme.md for overall project setup and usage.
• Review docs/sdk_usage.md for detailed SDK usage.
• Review docs/webhook_guide.md for webhook instructions.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/sdk
__init__.py	0	0	100%
client.py	39	0	100%
src/sdk/features
__init__.py	0	0	100%
contacts.py	38	0	100%
messages.py	30	2	2	93%
src/sdk/schemas
__init__.py	0	0	100%
contacts.py	18	1	1	94%
messages.py	17	0	100%
src/sdk/utils
__init__.py	0	0	100%
exceptions.py	52	9	9	83%
logger.py	22	0	100%
requests.py	15	4	4	73%
retry.py	21	1	1	95%
validators.py	62	2	2	97%
src/server
__init__.py	0	0	100%
app.py	25	3	3	88%
schemas.py	7	0	100%
TOTAL	346	22	94%

Tests	Skipped	Failures	Errors	Time
56	0 💤	0 ❌	0 🔥	6.832s ⏱️