Fixes (labs42io#22)

* Fixed usage of for-in loop in iterator example.

* Fixed typos.

Author: fuzzknob

README.md

@@ -1032,7 +1032,7 @@ function* fibonacci(): IterableIterator<number> {
 
 function print(n: number) {
   let i = 0;
-  for (const fib in fibonacci()) {
+  for (const fib of fibonacci()) {
     if (i++ === n) break;  
     console.log(fib);
   }  
@@ -1070,7 +1070,7 @@ itiriri(fibonacci())
 ### Use getters and setters
 
 TypeScript supports getter/setter syntax.
-Using getters and setters to access data from objects that encapsulate behavior could be better that simply looking for a property on an object.
+Using getters and setters to access data from objects that encapsulate behavior could be better than simply looking for a property on an object.
 "Why?" you might ask. Well, here's a list of reasons:
 
 - When you want to do more beyond getting an object property, you don't have to look up and change every accessor in your codebase.
@@ -1686,7 +1686,7 @@ class HttpRequester {
 
 This is a scary term for a very simple concept. It's formally defined as "If S is a subtype of T, then objects of type T may be replaced with objects of type S (i.e., objects of type S may substitute objects of type T) without altering any of the desirable properties of that program (correctness, task performed, etc.)." That's an even scarier definition.  
 
-The best explanation for this is if you have a parent class and a child class, then the base class and child class can be used interchangeably without getting incorrect results. This might still be confusing, so let's take a look at the classic Square-Rectangle example. Mathematically, a square is a rectangle, but if you model it using the "is-a" relationship via inheritance, you quickly get into trouble.
+The best explanation for this is if you have a parent class and a child class, then the parent class and child class can be used interchangeably without getting incorrect results. This might still be confusing, so let's take a look at the classic Square-Rectangle example. Mathematically, a square is a rectangle, but if you model it using the "is-a" relationship via inheritance, you quickly get into trouble.
 
 **Bad:**