Suggestion: add examples using the `examples/` directory

[pepedinho]

Rust allows crates to expose usage demonstrations by adding an examples/ directory at the root of the project.
This could be a great way to show how to use the library and make it easier for users to get started.

For example, the project structure could look like this:

.
├── Cargo.lock
├── Cargo.toml
├── examples
│        └── ... #here we can add main examples
└── src
    ├── functions
    │   ├── cosine.rs
    │   ├── cross_product.rs
    │   ├── linear_combination.rs
    │   ├── linear_interpolation.rs
    │   └── mod.rs
    ├── lib.rs
    ├── macros
    │   ├── arithmetics.rs
    │   └── mod.rs
    ├── matrix
    │   ├── arithmetics.rs
    │   └── functions
    │       ├── determinant.rs
    │       ├── inverse.rs
    │       ├── mod.rs
    │       ├── rank.rs
    │       ├── row_echelon.rs
    │       ├── trace.rs
    │       └── transpose.rs
    ├── matrix.rs
    ├── rows.rs
    ├── vector
    │   ├── arithmetics.rs
    │   └── functions
    │       ├── dot_product.rs
    │       ├── mod.rs
    │       └── norm.rs
    └── vector.rs

Each file in the examples/ directory could demonstrate a concrete use case (vector operations, matrix functions, etc.) and can be run with:

cargo  run --example example_name

I think this would greatly improve the usability and documentation of the crate.
Let me know what you think!