Refactor example tables in joins.md for clarity

Updated the example tables in the joins section to remove HTML entities and improve readability.

Author: dakshdeepHERE

content/sql/concepts/joins/joins.md

@@ -55,24 +55,24 @@ For example, here's the `shirts` table:
 
 | shirt_color |
 | ----------- |
-| 'white'     |
-| 'grey'      |
+| white     |
+| grey      |
 
 And the `pants` table:
 
 | pants_color |
 | ----------- |
-| 'light'     |
-| 'dark'      |
+| light     |
+| dark      |
 
 The result of the query would contain every combination of the two tables:
 
 | shirt_color | pants_color |
 | ----------- | ----------- |
-| 'white'     | 'light'     |
-| 'white'     | 'dark'      |
-| 'grey'      | 'light'     |
-| 'grey'      | 'dark'      |
+| white     | light     |
+| white     | dark      |
+| grey      | light     |
+| grey      | dark      |
 
 ## UNION