docs: adding request/reply content in module-3

[TRohit20]

Description
As part of creating a 100-level interactive learning path for AsyncAPI, adding the content for module 3.

Outline for the content to be present in the module from this pull request:

Module-3: AsyncAPI Specification

• Understanding the structure of an AsyncAPI document.
• request/reply

Spaceship fixed, we see Chan leaving to his planet on his spaceship

NOTE: This PR is the 3rd and final PR used to add content for module-3

[TRohit20]

Since Lukasz is currently on time off, I request @smoya to have a look and review the content, suggest changes(if any required) or approve if it all looks good.

Context: The PR is part of multiple PRs covering different sections of a single module(3):

• docs: adding content for module 3 #9 Adds about the structure of an AsyncAPI document
• docs: add content for module 3 #5 Adds necessary content WRT basic components and sections of an AsyncAPI document
• docs: adding request/reply content in module-3 #11 (Current PR in context) adds content solely about request/reply pattern
  Make sense?

Thanks!

CC @alequetzalli

[quetzalliwrites]

@TRohit20 I think you inadvertently may confuse Sergio with the PR order you discussed above... 😸

I would recommend instead you make a simple 3 point bullet list showing him the order of the PRs and title what each one covers.

[TRohit20]

Done @alequetzalli

[smoya]

I noticed there are 3 PR's opened pointing to the exact same file step2.md.

• docs: add content for module 3 #5
• docs: adding content for module 3 #9
• docs: adding request/reply content in module-3 #11

Please unify all of those into one single PR so we can review the file as a whole.

cc @TRohit20 @mhmohona @alequetzalli