Updated Dynamic Programming Section with More Examples

[s-tuti]

PR Description

1. Added Content and Code for :
   • String Edit Distance Problem
   • Matrix Chain Multiplication
   • Optimal Binary Search Tree
2. Updated the dynamic-programming.md

Related Issues

• Closes #1090

Checklist

• [x] I have gone through the contributing guide
• [x] I have updated my branch and synced it with project main branch before making this PR

Undertaking

I declare that:

1. The content I am submitting is original and has not been plagiarized.
2. No portion of the work has been copied from any other source without proper attribution.
3. The work has been checked for plagiarism, and I assure its authenticity.

I understand that any violation of this undertaking may have legal consequences that I will bear and could result in the withdrawal of any recognition associated with the work.

• [x] I Agree