docs: add Javadoc documentation for Library Book class

WHAT was added:
- Created `JAVADoc` class as a demo for Java documentation comments.
- Added metadata tags at the top of the file:
  • @author → Somesh Diwan
  • @Version → 1.0
  • @SInCE → 2025
- Documented a static field `val` with @value indicating its default value.
- Provided Javadoc for constructor and methods with appropriate tags:
  • @param → describes method parameters (e.g., book name, roll number, ID).
  • @throws → documents possible exceptions (in `issue()` method).
  • @return → explains return values (boolean for availability, String for book name).

KEY LEARNINGS:
1. Javadoc Tags:
   - @author → credits class author.
   - @Version → specifies version of class.
   - @SInCE → indicates when feature/class was introduced.
   - @param → explains parameters of method/constructor.
   - @return → explains returned value of method.
   - @throws → documents exceptions a method may throw.
   - @value → documents constant values.

2. Benefits:
   - Generates professional HTML documentation using `javadoc` tool.
   - Makes APIs self-explanatory and easier for other developers.
   - Acts as a single source of truth for class behavior and usage.

REAL-WORLD APPLICATIONS:
- ✅ Library or API design: Every public method and class is documented for external users.
- ✅ Enterprise projects: Standard practice for maintainability and onboarding new developers.
- ✅ Open-source contributions: Essential for community-driven projects to explain features clearly.
- ✅ IDE Integration: Tools like IntelliJ and Eclipse show Javadoc tooltips inline for better developer productivity.

RULE OF THUMB:
- Always document public classes, methods, and fields.
- Use concise but clear descriptions.
- Include @throws and @return wherever applicable.
- Keep Javadoc updated as code evolves.

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

Author: Someshdiwan

Section21AnnotationsandJavaDoc/src/JAVADocumentaion.java renamed to Section21AnnotationsandJavaDoc/src/JAVADoc.java

@@ -10,8 +10,7 @@
  * Class for Library Book
  */
 
-public class JAVADocumentaion
-{
+public class JAVADoc {
 
     /**
      * @value 10 default value
@@ -24,7 +23,7 @@ public class JAVADocumentaion
      * @param s Book Name
      */
 
-    public JAVADocumentaion(String s){
+    public JAVADoc(String s){
     }
 
     /**
@@ -52,4 +51,4 @@ public boolean available(String str){
     public String getName(int id){
         return "";
     }
-}
+}