Added new if-then-else example (Closes #71)

[RoaaFouda]

What kind of change does this PR introduce?

• New documentation.

Issue Number:

• Closes Add a task showing usage of if with nontrivial schema #71

If relevant, did you update the documentation?
No

Summary
I added a new example in the conditionals section that demonstrates the use of the minimum and not keywords with if-then-else. As mentioned in #71, this example was needed to provide more depth, as the existing examples primarily relied on constants. I would appreciate any feedback or suggestions for improvements to make this example even better.

Does this PR introduce a breaking change?

• No

[erosb]

Hello @RoaaFouda , thank you for raising the PR. I personally like it, for me it is a complex-enough demonstration of if-then-else, but not overly complex.

@JeelRajodiya @sandrina-p can you please take a look at it as well?

[RoaaFouda]

Hi @erosb, I'm glad to hear that :)
I'm waiting for any additional feedback from @JeelRajodiya and @sandrina-p in case any changes are needed.

[JeelRajodiya]

@RoaaFouda thanks for the PR, the new lesson looks great! We are merging it.