Update index.md and provide additional examples (#28758)
Update index.md and provide additional examples (#28758)

I added several additional examples of how to create and access an array.
BhaveshSGupta/FreeCodeCamp,jonathanihm/freeCodeCamp,BhaveshSGupta/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,raisedadead/FreeCodeCamp,FreeCodeCamp/FreeCodeCamp,raisedadead/FreeCodeCamp,FreeCodeCamp/FreeCodeCamp,jonathanihm/freeCodeCamp