Added Deque

[VaishnaviMankala19]

PR Description

I have added deque in ds-algorithms section which contains

• definition , syntax , examples , advantages , disadvantages , applications of deque

• updated index,md under ds-algorithms section

  Related Issues

• Closes #1244

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

[ashitaprasad]

All operations must be shown one by one in separate sub-sections

[VaishnaviMankala19]

sure