Update README.md

[bhavishyaone]

1. Table of Contents Added

   • Included a Table of Contents to help readers quickly find each section.

2. Emojis for Better Look

   • Added a few emojis to make sections stand out and look more interesting.

3. Clearer Section Titles

   • Updated titles to be clearer, like changing to What is Mimir? for a friendlier tone.

4.More Spacing for Easy Reading

• Added extra lines and dividers between sections to make the text easier to read.

5. Explained Structure Section

   • Gave a brief description of each part of Mimir (like Mimir, Mimir.Worker, MongoDB) before the diagram.

6. Highlighted Example Link in Applications

   • Made the link in the Applications section easier to see and added some introductory text.

7. Simple Language Edits

   • Rephrased some sentences for a smoother read and clearer meaning.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[boscohyun]

@bhavishyaone Thanks for your kind contribute!

Please check this Contributor License Agreement!

[moreal]

How do you think about this change? @boscohyun @Atralupus

Personally, I like GitHub-flavored markdown.