Corrected capitalization, corrected to American spellings and typos (#30685)

* Translate challenge subtitles and example challenge text to Spanish

* Corrected errors in syntax and punctuation

* Multiple corrections of it/s to its plus other grammar corrections

* Correction and added paragraph to CSS Flex article

* Corrected my own typo

* Corrected capitalization, American spellings and typos

guide/english/certifications/javascript-algorithms-and-data-structures/basic-algorithm-scripting/chunky-monkey/index.md

@@ -186,7 +186,7 @@ Finally, we need a method to do the actual splitting and we can use `Array.slice
 ### Code Explanation:
 
 * Array smaller than size is returned nested.
-* For any array larger than size, it's splited in two. First segment is nested and concatnated with second second segment which makes a recursive call.
+* For any array larger than size, it is split in two. First segment is nested and concatenated with second segment which makes a recursive call.
 
 #### Relevant Links
 

guide/english/certifications/javascript-algorithms-and-data-structures/basic-algorithm-scripting/title-case-a-sentence/index.md

@@ -62,7 +62,7 @@ We have to return a sentence with title case. This means that the first letter w
 
 We are modifying the `replaceAt` function using prototype to facilitate the use of the program.
 
-Split the string by white spaces, and create a variable to track the updated title. Then we use a loop to turn turn the first character of the word to uppercase and the rest to lowercase. by creating concatenated string composed of the whole word in lowercase with the first character replaced by it's uppercase.
+Split the string by white spaces, and create a variable to track the updated title. Then we use a loop to turn turn the first character of the word to uppercase and the rest to lowercase. by creating concatenated string composed of the whole word in lowercase with the first character replaced by its uppercase.
 
 #### Relevant Links