docs: Improve Best Practices Guide for Elysia.js

[Ahmedabbas03]

This pull request improves the Best Practices guide for Elysia.js. The updates make the content clearer and more consistent.

Key Improvements

• Grammar & Clarity

  • Corrected grammatical errors for better readability.
  • Improved sentence structure for clearer explanations.

• Consistency

  • Used a uniform writing style (e.g., consistently referring to "Elysia.js" or "Elysia").
  • Standardized phrasing (e.g., "should" vs. "recommended").

• Code Readability

  • Maintained consistent formatting and indentation.
  • Added concise comments where necessary for clarity.
  • The section on method chaining now explains its importance for type integrity.
  • The controller section is simplified to keep things clear and type-safe.
  • The services section shows how to create non-request dependent services with better examples.

These changes aim to help developers follow best practices when using Elysia.js.