Embedded the CV overview video in introduction documentation

[Murdock9803]

Fixes #353

Changes done:

• [x] Removed the [CV Marketing Video] text.
• [x] Embedded the CircuitVerse Overview video from youtube in the Introduction page bottom.

Screenshots:

before :

after :

Preview Link(s):

https://github.com/CircuitVerse/CircuitVerseDocs/pull/358/files#diff-be8049532e9abd127315370c8ffc90a920275c5fb3d7a4dfe197d0a225fa7946

✅️ By submitting this PR, I have verified the following

• [x] Checked to see if a similar PR has already been opened 🤔️
• [x] Reviewed the contributing guidelines 🔍️
• [x] Sample preview link added (add a link from the checks tab after checks complete)
• [x] Tried Squashing the commits into one

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[Murdock9803]

Thank you very much 🚀

[Murdock9803]

@tachyons as the changes are approved, please take a look at the PR.