docs: update parallel-stream content

Author: masiljangajji

exercises/practice/parallel-letter-frequency/.approaches/parallel-stream/content.md

@@ -38,10 +38,10 @@ Using [`ConcurrentHashMap`][ConcurrentHashMap] ensures that frequency counting a
 If there are no strings to process, a validation step avoids unnecessary computation.
 
 To calculate letter frequency, a parallel stream is used.  
+The [`Character.isAlphabetic`][isAlphabetic] method identifies all characters classified as alphabetic in Unicode, covering characters from various languages like English, Korean, Japanese, Chinese, etc., returning `true`. 
+Non-alphabetic characters, including numbers, special characters, and spaces, return `false`.
 
-The [`Character.isAlphabetic`][isAlphabetic] method identifies all characters classified as alphabetic in Unicode, covering characters from various languages like English, Korean, Japanese, Chinese, etc., returning true. Non-alphabetic characters, including numbers, special characters, and spaces, return false.
-
-Since we treat uppercase and lowercase letters as the same character (e.g., A and a), characters are converted to lowercase.
+Since we treat uppercase and lowercase letters as the same character (e.g., `A` and `a`), characters are converted to lowercase.
 
 After updating letter frequencies, the final map is returned.