Update fibonacci-solution.js: add recursive solution

[AdishtJaglan]

Added the recursive approach to the solution.

Because

This PR also add a recursive solution to the question at hand. It might create some curiousity in the mind of the reader, which might lead to greater interest.

This PR

• Added comments which include a recursive solution, complementing the iterative solution.

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. 01_helloWorld: Update test cases
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If this PR includes any changes that affect the solution of an exercise, I've also updated the solution in the /solutions folder

[MaoShizhong]

@AdishtJaglan Thank you for submitting this PR.

Introducing recursion here would not be pedagogically appropriate. This is likely to cause more confusion and questions for learners than beneficial knowledge. It also risks opening a huge rabbit hole into recursion way before it's appropriate to dive into that topic.

Recursion is taught later on in either full-stack pathway at a time that is more appropriate within the course. At this point, learners can then benefit from the structured guidance the course provides.

Diving into recursion without guidance and at a much earlier point in the course where learners will have far less experience with the tools and concepts in general, that doesn't seem like the best idea to me.