Rajiv's 1st restructuring attempt

Ok, I changed the navigation around in addition to moving some of the content around.
I think this code block is a bit to descriptive of what you can do with `LYRMessagePart` objects. Maybe you could use the factory method that generates a plain text part with a one liner instead.
```objective-c
LYRMessagePart *messagePart = [LYRMessagePart messagePartWithText:@"Hi, how are you?"];
```