Expanded explanation, added links (#21157)
Expanded explanation, added links (#21157)

* Expanded explanation, added links

The earlier version of this did not expand fully on usage patterns or how SSH operates. I added an explanation of why you don't need to specify the username, additional examples, and links for further investigation.

* Update index.md

BhaveshSGupta/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,FreeCodeCamp/FreeCodeCamp,jonathanihm/freeCodeCamp,FreeCodeCamp/FreeCodeCamp,raisedadead/FreeCodeCamp,jonathanihm/freeCodeCamp,raisedadead/FreeCodeCamp