Update Introduction docs page to "Lightning in 2 Steps"

[kaushikb11]

What does this PR do?

We are reverting back the Introduction page to previous version.

The current Introduction page has a lot of details which could be narrowed down to "Lightning in 2 Steps"

Does your PR introduce any breaking changes? If yes, please list them.

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Did you have fun?

Make sure you had fun coding 🙃

cc @Borda @rohitgr7

[rohitgr7]

just some thoughts!