CON-2533-Markdown-Multiplication-Table-exercise (#2521)

* docs: adding subject

* docs: fixing format

* docs: fix minor typos

---------

Co-authored-by: amine <aaitihia@leyton.com>

subjects/java/checkpoints/multiplication-table/README.md

@@ -0,0 +1,45 @@
+## MultiplicationTable
+
+### Instructions
+
+In a file named `MultiplicationTable.java` write a function `generate` which takes a number as a parameter, and prints the multiplication table for this number.
+
+### Expected Functions
+
+```java
+public class MultiplicationTable {
+    public static void generate(int num) {
+        // your code here
+    }
+}
+```
+
+### Usage
+
+Here is a possible `ExerciseRunner.java` to test your function :
+
+```java
+public class ExerciseRunner {
+    public static void main(String[] args) {
+        MultiplicationTable.generate(5);
+    }
+}
+```
+
+and its output :
+
+```shell
+$ javac *.java -d build
+$ java -cp build ExerciseRunner
+5 x 1 = 5
+5 x 2 = 10
+5 x 3 = 15
+5 x 4 = 20
+5 x 5 = 25
+5 x 6 = 30
+5 x 7 = 35
+5 x 8 = 40
+5 x 9 = 45
+5 x 10 = 50
+$
+```