Talk about examples in the documentation

examples/README.md

@@ -0,0 +1,5 @@
+# argmin examples
+
+Every solver and most features of argmin are showcased in this examples directory.
+Each example is a dedicated Rust crate with a corresponding `Cargo.toml`, which includes all relevant dependencies to run it.
+Make sure that the examples you are looking at match the argmin version you are using be choosing the appropriate Git version tag on Github.

media/book/src/contributing.md

@@ -31,7 +31,7 @@ cargo test -p argmin-math
 Or the default features plus the latest `ndarray`/`nalgebra` backends:
 
 ```bash
-cargo test -p argmin-math --features "latest_all,_dev_linalg_latest"
+cargo test -p argmin-math --features "latest_all"
 ```
 
 Individual backends can be tested as well; however, care has to be taken to not add two different versions of the same backend, as that may not work.

media/book/src/using_argmin.md

@@ -45,3 +45,9 @@ For performance reasons, the latter two should be preferred. Which one to use is
 
 `Vec`s on the other hand do not have very efficient implementations for the different mathematical operations and therefore are not well suited for solvers which heavily rely on matrix operations.
 However, `Vec`s are suitable for solvers such as Simulated Annealing and Particle Swarm Optimization, which mainly operate on the parameter vectors themselves. 
+
+## Examples
+
+Every solver and most features of argmin are showcased in the [examples directory](https://github.com/argmin-rs/argmin/tree/main/examples).
+Each example is a dedicated Rust crate with a corresponding `Cargo.toml`, which includes all relevant dependencies to run it.
+Make sure that the examples you are looking at match the argmin version you are using be choosing the appropriate Git version tag on Github.