Changelog for NSE

`v0.1.2`

11.05.2022

Updated to nse 0.1.2

Changed

Fixed Isahc version to 1.7.1 instead of git master branch due to failing curl-sys build
Commented code better

`v0.1.1`

10.05.2022

Updatd to nse 0.1.1
Improved upgrade code to be faster and more clean
Immediately fail if rate limit error occured
Show the http requests response status alongwith timetaken and no of retries it took while completing the request.

Added

This changelog
Command line interface and corresponding code (under progress with cli.rs and cli.yaml)
NetworkData & OhlcvRecord struct for nsefetch
JSON file write
does_exist() function for checking if a mod exists
Error codes

Changed

Moved util.rs to nse mod folder
Made all panics into println!s and exits (with descriptive error codes)
Commented code better