Fix some issues in 9.2 (Character classes)

9-regular-expressions/02-regexp-character-classes/article.md

@@ -8,7 +8,7 @@ A *character class* is a special notation that matches any symbol from a certain
 
 For the start, let's explore the "digit" class. It's written as `pattern:\d` and corresponds to "any single digit".
 
-For instance, the let's find the first digit in the phone number:
+For instance, let's find the first digit in the phone number:
 
 ```js run
 let str = "+7(903)-123-45-67";
@@ -144,10 +144,10 @@ That's what flag `pattern:s` does. If a regexp has it, then a dot `pattern:.` ma
 alert( "A\nB".match(/A.B/s) ); // A\nB (match!)
 ```
 
-````warn header="Not supported in Firefox, IE, Edge"
-Check <https://caniuse.com/#search=dotall> for the most recent state of support. At the time of writing it doesn't include Firefox, IE, Edge.
+````warn header="Not supported in IE"
+The `pattern:s` flag is not supported in IE.
 
-Luckily, there's an alternative, that works everywhere. We can use a regexp like `pattern:[\s\S]` to match "any character".
+Luckily, there's an alternative, that works everywhere. We can use a regexp like `pattern:[\s\S]` to match "any character" (this pattern will be covered in the article <info:regexp-character-sets-and-ranges>).
 
 ```js run
 alert( "A\nB".match(/A[\s\S]B/) ); // A\nB (match!)
@@ -179,7 +179,7 @@ alert( "1 - 5".match(/\d\s-\s\d/) ); // 1 - 5, also works
 
 **A space is a character. Equal in importance with any other character.**
 
-We can't add or remove spaces from a regular expression and expect to work the same.
+We can't add or remove spaces from a regular expression and expect it to work the same.
 
 In other words, in a regular expression all characters matter, spaces too.
 ````
@@ -198,6 +198,6 @@ There exist following character classes:
 
 ...But that's not all!
 
-Unicode encoding, used by JavaScript for strings, provides many properties for characters, like: which language the letter belongs to (if it's a letter) it is it a punctuation sign, etc.
+Unicode encoding, used by JavaScript for strings, provides many properties for characters, like: which language the letter belongs to (if it's a letter), is it a punctuation sign, etc.
 
 We can search by these properties as well. That requires flag `pattern:u`, covered in the next article.