Update README.

Also change introduction.md which copies from README (because README isn't in the rendered book).

README.md

@@ -1,27 +1,54 @@
 # Rust Exercises
 
-This book contains a collection of Rust Exercises, written by Ferrous Systems.
+This book contains a collection of Rust Exercises, written by Ferrous Systems. See [ferrous-systems.com/training](https://ferrous-systems.com/training) for more details or a custom quote. You can view this material on-line at <https://rust-exercises.ferrous-systems.com>.
 
 We use these exercises as part of our [Rust Training](https://ferrous-systems.com/training/), but you are welcome to try them for yourself as well.
 
-If you wish to fund further development of the course, why not [book a training with us](https://ferrous-systems.com/training/)!.
+If you wish to fund further development of the course, why not [book a training with us](https://ferrous-systems.com/training/)!
 
 # Reading the book
 
 You can:
 
+* View the `main` branch on-line at <https://rust-exercises.ferrous-systems.com/latest/book>
+* View a specific tag like `v1.10.0` at <https://rust-exercises.ferrous-systems.com/v1.10.0/book>
 * Browse [the chapters of the book on Github](./exercise-book/src/SUMMARY.md)
 * Browse [the exercises on Github](./exercise-templates)
 * Browse [the solutions on Github](./exercise-solutions)
-* Clone the repo, and build the book using [`mdbook`](https://crates.io/crates/mdbook)
-* Download the book in HTML format, with solutions and templates, from the [releases area](https://github.com/ferrous-systems/rust-exercises/releases)
+* Clone the repo, and build the book (see [Building the material locally](#building-the-material-locally))
+* Download the book in HTML format for off-line use, with solutions and templates, from the [releases area](https://github.com/ferrous-systems/rust-exercises/releases)
 
-# License
+## Building the material locally
+
+To build the exercise book, run `mdbook` in the usual fashion:
+
+```console
+$ cargo install mdbook
+$ cargo install mdbook-mermaid
+$ cd ./exercise-book
+$ mdbook build
+2024-07-01 11:51:21 [INFO] (mdbook::book): Book building has started
+2024-07-01 11:51:21 [INFO] (mdbook::book): Running the html backend
+$ ls -l book/index.html
+-rw-r--r--  1 jonathan  staff  27975  1 Jul 11:51 book/index.html
+```
+
+You could use `mdbook serve` instead to start a webserver that serves up the book and also rebuilds the book every time you change a file.
+
+To verify that every code example in the book compiles as expected, run:
+
+```sh
+mdbook test
+```
+
+To verify that all the examples build, we use the top-level build script `build.sh`. Note that running that script may require a valid CriticalUp token, as we use Ferrocene in our CI.
+
+## License
 
 [![Creative Commons License](https://i.creativecommons.org/l/by-sa/4.0/88x31.png)](http://creativecommons.org/licenses/by-sa/4.0/)
 
 This work is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/).
 
 We encourage the use of this material, under the terms of the above license, in the production and/or delivery of commercial or open-source Rust training programmes.
 
-Copyright (c) Ferrous Systems, 2023
+Copyright (c) Ferrous Systems, 2024

exercise-book/src/introduction.md

@@ -1,6 +1,6 @@
 # Introduction
 
-This book contains a collection of Rust Exercises, written by Ferrous Systems.
+This book contains a collection of Rust Exercises, written by Ferrous Systems. See [ferrous-systems.com/training](https://ferrous-systems.com/training) for more details or a custom quote. You can view this material on-line at <https://rust-exercises.ferrous-systems.com>.
 
 We use these exercises as part of our [Rust Training](https://ferrous-systems.com/training/), but you are welcome to try them for yourself as well.
 
@@ -33,4 +33,4 @@ This work is licensed under a [Creative Commons Attribution-ShareAlike 4.0 Inter
 
 We encourage the use of this material, under the terms of the above license, in the production and/or delivery of commercial or open-source Rust training programmes.
 
-Copyright (c) Ferrous Systems, 2023
+Copyright (c) Ferrous Systems, 2024