feat: demonstrate markSupported() with ByteArrayInputStream

WHAT:
- Added `ByteStreamExample2` to verify `mark()`/`reset()` support on
  `ByteArrayInputStream`.
- Created a byte array of characters ('a' through 'j') as the input source.
- Used `readAllBytes()` to consume the full stream into a string (not printed here).
- Invoked `markSupported()` to check if the stream supports marking and resetting.
- Printed the result (`true` for ByteArrayInputStream).
- Closed the stream at the end.

WHY:
- `markSupported()` is an important method in Java I/O that tells whether a
  stream allows repositioning back to a previously marked position.
- `ByteArrayInputStream` always supports `mark()` and `reset()` because it is
  memory-based, making rewinding safe and efficient.
- Demonstrates good practice to check `markSupported()` before using `mark()`
  and `reset()` with other stream types (e.g., `FileInputStream` does not support it).

HOW:
1. Created a byte array with letters a–j.
2. Wrapped it with `ByteArrayInputStream`.
3. Consumed the entire stream with `readAllBytes()`.
4. Called `markSupported()`, which returned `true`.
5. Printed the result to confirm support for `mark()`/`reset()`.
6. Closed the stream.

REAL-WORLD USE CASES:
- Marking and resetting are useful for parsers, scanners, or network protocols
  where peeking ahead is required.
- Example: checking headers in a stream before deciding how to parse payload.
- `ByteArrayInputStream` is often used in unit tests to simulate input data
  where mark/reset behavior is guaranteed.

NOTES:
- Once `readAllBytes()` is called, the stream is fully consumed; resetting
  after that without explicitly marking is meaningless.
- A better demo could combine `mark()`, some reads, then `reset()` to show
  actual rewinding.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section23JavaIOStreams/src/ByteStreamExample2.java

@@ -2,7 +2,7 @@
 
 public class ByteStreamExample2 {
     public static void main(String[] args)throws Exception {
-        byte b[]={'a', 'b','c','d','e','f','g','h','i','j'};
+        byte b[] = {'a', 'b','c','d','e','f','g','h','i','j'};
 
         ByteArrayInputStream bis = new ByteArrayInputStream(b);
         //Mark&Rest() method checking.