Add instructions for using this lib to validate address in general JAVA project

[Tianhao25]

I found we don't have an instruction to tell users how to use this lib inside general JAVA project. I wrote an instruction based on my explorations to this lib.

[googlebot]

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[Tianhao25]

I signed it!

[googlebot]

CLAs look good, thanks!

[michelazzo]

CLAs look good, thanks... And merge it! Come one, merge!