Add doc for Renode usage notes.

Create a document to keep track of and pool Renode examples and usage
notes.

To be included, Renode script setup, adding extensions in C#, and
Robot workflow.

(Also added small typo-fix in RunningOpenTitanVectorSimulation.md)

Change-Id: Id6f462bd76f35e43667748b28113c1f4e5bcc67e