Provide example documentation around the use of deadlines in gRPC

[hsaliak]

This should cover common questions such as:

• How to use it? What is the provided API?
• How do I specify the deadline? Common patterns in doing this.
• What happens when deadline is reached and how do I handle such exception/error?
• Error/Exception handling for deadlines?
• Patterns on cancelling in-progress tasks when deadline is reached? How do I receive this notification and cancel server tasks? How does this propagate to the other calls. What happens when the propagation fails?

Implementation order

• [ ] Java
• [ ] Go
• [ ] Wrapped language eg C#/Python