Rewrite README for Arshad Mehmood's personal blog

[arshad115]

Motivation

• Replace the upstream Minimal Mistakes boilerplate with a focused README that describes this repository as a personal blog.
• Present the site's purpose and audience in a concise, personable voice with emojis for clarity and character.
• Remove irrelevant theme-maintainer and licensing wall-of-text so visitors see only what's useful for this specific site.

Description

• Replaced the existing README.md content with a concise, blog-specific landing document titled "👋 Welcome to Arshad Mehmood's Blog".
• Added sections describing the site's purpose (✨ What this site is about), tech stack (🧰 Tech stack), project layout (🗂️ Project structure (quick view)), local run steps (🧪 Run locally), live site URL, and social/contact links.
• Removed large upstream theme documentation, demo pages, credits, and license blocks to keep the repository README targeted and readable.
• Kept local run instructions with the commands bundle install and bundle exec jekyll serve and included the live site URL https://arshadmehmood.com.

Testing

• Attempted to validate the site by running bundle exec jekyll build --quiet, which failed in this environment with bundler: command not found: jekyll due to missing gem executables.

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Codex Task