Add String Examples

[MayankSingh1993]

Examples of any form of String Implitation are permitted.

[smscoder-7]

assign me pls

[SaxenaAnushka102]

Hello @MayankSingh1993 ! I'd like to contribute, please assign the issue.

[smscoder-7]

@MayankSingh1993 added string program - palindrome, please check and merge

[MayankSingh1993]

@SaxenaAnushka102 You can add any functional Java code you created to this repository. If you could help, that would be great.