Fixed errors and improved readability

nostarch/chapter02.md

@@ -278,9 +278,9 @@ on which variant an enum value is when the conditional is evaluated.
 Chapter 6 will cover enums in more detail. The purpose of these `Result` types
 is to encode error-handling information.
 
-`Result`’s variants are `Ok` or `Err`. The `Ok` variant indicates the
-operation was successful, and inside `Ok` is the successfully generated value.
-The `Err` variant means the operation failed, and `Err` contains information
+`Result`’s variants are `Ok` and `Err`. The `Ok` variant indicates that the
+operation was successful, and it contains the successfully generated value.
+The `Err` variant means the operation failed, and it contains information
 about how or why the operation failed.
 
 Values of the `Result` type, like values of any type, have methods defined on

nostarch/chapter03.md

@@ -76,7 +76,7 @@ isn’t safely doing what you want it to do yet; they do *not* mean that you’r
 not a good programmer! Experienced Rustaceans still get compiler errors.
 
 The error message indicates that the cause of the error is that you `` cannot
-assign twice to immutable variable `x` ``, because you tried to assign a second
+assign twice to immutable variable ``, because you tried to assign a second
 value to the immutable `x` variable.
 
 It’s important that we get compile-time errors when we attempt to change a

nostarch/chapter04.md

@@ -95,7 +95,7 @@ strings.
 > data on the heap so you don’t run out of space are all problems that ownership
 > addresses. Once you understand ownership, you won’t need to think about the
 > stack and the heap very often, but knowing that the main purpose of ownership
-> is to manage heap data can help explain why it works the way it does.
+> is to manage heap data and can help explain why it works the way it does.
 
 ### Ownership Rules
 
@@ -150,7 +150,7 @@ understanding by introducing the `String` type.
 
 To illustrate the rules of ownership, we need a data type that is more complex
 than those we covered in the “Data Types” section of Chapter 3. The types
-covered previously are all a known size, can be stored on the stack and popped
+covered previously are all of a known size, can be stored on the stack and popped
 off the stack when their scope is over, and can be quickly and trivially copied
 to make a new, independent instance if another part of code needs to use the
 same value in a different scope. But we want to look at data that is stored on