Create README.md

To start application:

1. "ContactManager" folder has my project related files.
2. ContactManager.java has the main method.
3.  I have complied all the classes already. 
4. "java ContactManager" command would start my application

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IMPORTANT if compilation is done again:

1. The txt file which holds the data is "sampleData.txt".
2. In the Service.java class, I have given path to the file (local path of my PC)
3. Please change the path of the file in Service.java class if comiling again.
4. If this is not done, the application simply throws an error message on the screen