Add info about Prototypes in JavaScript

[Swap76]

Add the info in prototypes.md placed in docs/JavaScriptAdvance

Use the example given in JavaScript_Advance for explaining Prototypes

You can also explain with more examples taking reference is ok but directly copying is not allowed

[dnafication]

Hi @Swap76, Can I take this? I have written the content. Will send the PR.

[Swap76]

@dnafication Cool