Adding Enum examples

[Tawishi]

Resolves #39

• Add Enum class by taking example (directory named enum)
• Add a few methods with explanation
• Add iteration methods
• Add readme in the directory

[SiddharthaAnand]

Please go over the review comments. Added hacktoberfest tag here.

[SiddharthaAnand]

Move all the constants to a final variable and use it instead of hardcoding them in here.

[Tawishi]

Do you mean the statements I am displaying?

[SiddharthaAnand]

Use other Enum in built methods as well and show their functionality here.

[Tawishi]

Could you please name a few?