[Docs] Overview of dynamic workflows from an execution POV

[kumare3]

Description

The blog explains the dynamic workflow concept - https://blog.flyte.org/dynamic-workflows-in-flyte, but we need to add it to the documentation also. A few things that should be highlighted

• [ ] dynamic is still compiled - so it can be visualized
• [ ] understanding how futures file works
• [ ] When to use dynamic workflows, lower pressure on etcD
• [ ] problem of large fan-out, compare and contrast dynamic vs map tasks
• [ ] overriding resources and config at runtime dynamically using dynamic workflows

Are you sure this issue hasn't been raised already?

• [X] Yes

Have you read the Code of Conduct?

• [X] Yes

[samhita-alla]

Fixes https://flyte-org.slack.com/archives/CNMKCU6FR/p1643105410130200?thread_ts=1642993031.095000&cid=CNMKCU6FR as well.