Adding Arithmetic & Bitwise operators - JS roadmap (#1878)

* Adding Arithmetic & Bitwise operators

* Rectified Typos in the existing files

content/roadmaps/106-javascript/content/112-javascript-asynchronous-javascript/104-promises/readme.md

@@ -1,6 +1,6 @@
 # Promises
 
-Promises are a much better way to work with asynchronous code in JavaScript than the old and error-prone callback approach. They were introduced into JavaScript with ECMAScript 6. Using promises, we can manage extremely complex asynchronous code with rigorous error-handling set up, write code in a more or less synchronous style, and keep ourselves from running into the so-called callback hell.
+Promises are a much better way to work with asynchronous code in JavaScript than the old and error-prone callback approach. They were introduced into JavaScript with ECMAScript 6. Using promises, we can manage extremely complex asynchronous code with rigorous error-handling setup, write code in a more or less synchronous style, and keep ourselves from running into the so-called callback hell.
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.codeguage.com/courses/advanced-js/promises-introduction'>A Detailed Introduction to Promises</BadgeLink>