docs(str): moving the actual documentation on the header

- The documentation on the header allow u to see on the files where the
header is inclued

str/ft_strnstr.c

@@ -6,26 +6,12 @@
 /*   By: rparodi <marvin@42.fr>                     +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/11/07 16:57:44 by rparodi           #+#    #+#             */
-/*   Updated: 2025/09/01 17:54:58 by rparodi          ###   ########.fr       */
+/*   Updated: 2025/09/05 16:17:50 by rparodi          ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <unistd.h>
 
-/**
- * @brief Locates a substring within a string, up to a specified length.
- * 
- * The `ft_strnstr` function locates the first occurrence of the null-terminated
- * string `needle` within the string `haystack`,
- * searching only up to `len` characters.
- * 
- * @param big The string to search.
- * @param little The substring to locate.
- * @param len The maximum number of characters to search.
- * 
- * @return A pointer to the beginning of the located substring,
- * or NULL if `needle` is not found.
- */
 char	*ft_strnstr(const char *big, const char *little, size_t len)
 {
 	size_t	i;