fix numArgs typo

The PR aims to fix the number of arguments provided in Part 1 of the README.

README.md

@@ -131,7 +131,7 @@ You'll need to create the following C files for this project:
 
 ## Part 1 --- `mkfs.c` (15% of the grade)
 
-This C program initializes a file to an empty filesystem. I.e. to the state, where the filesystem can be mounted and other files and directories can be created under the root inode. The program receives three arguments: the raid mode, disk image file (multiple times), the number of inodes in the filesystem, and the number of data blocks in the system. The number of blocks should always be rounded up to the nearest multiple of 32 to prevent the data structures on disk from being misaligned. For example:
+This C program initializes a file to an empty filesystem. I.e. to the state, where the filesystem can be mounted and other files and directories can be created under the root inode. The program receives four arguments: the raid mode, disk image file (multiple times), the number of inodes in the filesystem, and the number of data blocks in the system. The number of blocks should always be rounded up to the nearest multiple of 32 to prevent the data structures on disk from being misaligned. For example:
   ```sh
   ./mkfs -r 1 -d disk1 -d disk2 -i 32 -b 200
   ```