This PR implements the code for exponential search in javascript referred in issue #42.

[Ankitasareen]

This PR implements the code for in referred in issue #

I have read the contributing guidelines in CONTRIBUTING.md and have ensured the following:

• My code is placed in the required directory as outlined in CONTRIBUTING.md
• My code file is named according to CONTRIBUTING.md
• Variables, classes, functions etc. follow camel case as outlined in CONTRIBUTING.md
• My code hasn't been implemented or claimed by someone else and I have checked the present issues and PRs for the same
• My code is well commented
• If my code is the first implementation of , I have added the link to this directory in README.md
• I have not copied my code from anywhere

This PR creates/modifies the README for

I have read the contributing guidelines in CONTRIBUTING.md and have ensured the following:

• Algo name (as heading)
• A small description about algo
• Time Complexity (Worst, Average, Best case)
• Space Complexity (Worst, Average, Best case)
• Logic and Pseudocode
• Instructions for running code

[deutranium]

Please follow the conventions for file naming, variable naming etc. as outlined in CONTRIBUTING.md. They are there for a reason. After the changes for the same, I'll be able to merge this PR.