fixed spelling errors, added more information (#28297)

- logic changes
- explanations on different statements

guide/english/c/if/index.md

@@ -29,8 +29,7 @@ else {
 }
 ```
 
-Note that the `else` and `else if` sections are not required, while `if` is mandatory.
-
+Note: `else` and `else if` sections are not required, while `if` is mandatory. Furthermore, `else` and `else if` can only be used following an `if` statement. In the instance when one `if` statement is executed, the following `else if` and `else` statements are ignored.
 
 ## Example
 ```