Surface code demo (#1797)

**Title:**

Surface code demo

**Summary:**

Addin a demo on the basics of the surface code

**Relevant references:**

**Possible Drawbacks:**

**Related GitHub Issues:**

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If you are writing a demonstration, please answer these questions to
facilitate the marketing process.

* GOALS — Why are we working on this now?

*Eg. Promote a new PL feature or show a PL implementation of a recent
paper.*


* AUDIENCE — Who is this for?

*Eg. Chemistry researchers, PL educators, beginners in quantum
computing.*


* KEYWORDS — What words should be included in the marketing post?


* Which of the following types of documentation is most similar to your
file?
(more details
[here](https://www.notion.so/xanaduai/Different-kinds-of-documentation-69200645fe59442991c71f9e7d8a77f8))
    
- [ ] Tutorial
- [ ] Demo
- [ ] How-to

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Co-authored-by: drdren <104710745+drdren@users.noreply.github.com>
Co-authored-by: Utkarsh <utkarshazad98@gmail.com>

Author: 3 people