Make CONTRIBUTING.md more descriptive

Because of current version of CONTRIBUTING.md we are facing these problem:-

1. Missing Frontmatter: Contributors frequently forget to add the **frontmatter** to their blog posts, causing metadata issues.
2. Incorrect Image Handling: Instead of linking to images in the public folder, contributors often **copy and paste** images directly into the Markdown files. This unnecessarily increases the repository size and bypasses our image optimization process.
3. Inconsistent Writing Style: Blog posts sometimes lack a clear narrative **_flow_**. They often use excessive abbreviations without defining them first, which can confuse readers.
4. Lack of Guidance on Formulas: There is no clear recommendation for contributors to use the **.mdx format** when they need to include mathematical formulas, despite our support for LaTeX in MDX.

### **Task**

Update Contribution Guidelines (CONTRIBUTING.md)

- [ ] Add a mandatory checklist to the Pull Request template that requires contributors to confirm they have added the correct frontmatter.
- [ ] Create a clear section on how to handle images:
- Explain that all images must be placed in the /public/ directory.
- Provide a clear example of the correct Markdown syntax for linking images.
- Explicitly forbid embedding images directly into .md or .mdx files.
- [ ] Enhance the writing style guide:
- Emphasize the importance of storytelling and maintaining a logical flow.
- [ ] Add documentation for writing mathematical formulas:
- State that posts containing LaTeX formulas must use the .mdx file extension.
- [ ] Create a Blog Post Template
- Design a template file (template.mdx) that includes placeholder frontmatter and commented-out instructions for each section, including image and formula usage. This can serve as a starting point for new contributions.