2.5_exercise: Pointer to Diplomacy page is stale.

[BarrySi5]

The URL for the Diplomacy site in the following section of text:

DspBlocks use diplomatic interfaces from rocket. This site (https://www.lowrisc.org/docs/diplomacy/) has a good overview of the basic of diplomacy, but don't worry too much about how it's working for this example.

yields a "404 page not found" error.

The perhaps next closest reference I could find was:

https://github.com/Intensivate/learning-journey/wiki/Diplomacy

It also has a pointer to the same web page:
This is based on the Main Diplomacy Page (https://www.lowrisc.org/docs/diplomacy/)