Update top-level README

Change description of documentation in this repo
Add links to online resources on the P4 target and architecture

README.md

@@ -27,8 +27,16 @@ The description of each assignment is in it's respective folder.
     * [Controlled Load Balance](./assignments/controlled_load_balance/README.md)
 
 ## Resources
+This repo contains:
+* slides from the introductory lecture (`P4_Lab_Slides_2023.pdf`)
+* alternative slides from [p4.org](https://p4.org/) (`P4_tutorial.pdf`)
+* a P4 Cheat Sheet containing various examples that you can use (`p4-cheat-sheet.pdf`)
 
-Presentation slides are available [online](https://courses.sidnlabs.nl/anet-2023/) and alternative slides from p4.org are available in the P4_tutorial.pdf in this repository. A P4 Cheat Sheet is also available in this repository. This contains various examples that you can use. If you use code from any of these places, or from other places on the internet, please indicate so with a comment.
+All excercises in this repository use the v1model architecture, the documentation for which is available at:
+1. The BMv2 Simple Switch target document accessible [here](https://github.com/p4lang/behavioral-model/blob/master/docs/simple_switch.md) talks mainly about the v1model architecture.
+2. The include file `v1model.p4` has extensive comments and can be accessed [here](https://github.com/p4lang/p4c/blob/master/p4include/v1model.p4).
+
+If you use code from any of these places, or from other places on the internet, please indicate so with a comment.
 
 ## Obtaining required software