fix spelling error (#19)

Author: techgaun

chapters/ch01.asciidoc

@@ -69,7 +69,7 @@ A stage 3 candidate recommendation proposal is most likely to make it into the s
 
 Babel and similar compilers that take code as input and produce output native to the web platform (HTML, CSS or JavaScript) are often referred to as transpilers, which are considered to be a subset of compilers. When we want to leverage a proposal that's not widely implemented in JavaScript engines in our code, compilers like Babel can transform the portions of code using that new proposal into something that's more widely supported by existing JavaScript implementations.
 
-This transformation can be done at build-time, so that consumers receive code that's well supported by their JavaScript runtime of choice. This mechanism improves the runtime support baseline, giving JavaScript developers the ability to take advantage of new language features and syntax sooner. It is also significantly benefitial to specification writers and implementors, as it allows them to collect feedback regarding viability, desirability, and possible bugs or corner cases.
+This transformation can be done at build-time, so that consumers receive code that's well supported by their JavaScript runtime of choice. This mechanism improves the runtime support baseline, giving JavaScript developers the ability to take advantage of new language features and syntax sooner. It is also significantly beneficial to specification writers and implementors, as it allows them to collect feedback regarding viability, desirability, and possible bugs or corner cases.
 
 A transpiler can take the ES6 source code we write and produce ES5 code that browsers can interpret more consistently. This is the most reliable way of running ES6 code in production today: using a build step to produce ES5 code that any modern browser can execute.