message: Add note about `*latest*` features in argmin-math docs
diff: //!
  //! It is not possible to activate two versions of the same backend.
  //!
  -//! The features labelled `*_latest*` are an alias for the most recent supported version of the
  -//! respective backend.
  +//! The features labelled `*latest*` are an alias for the most recent supported version of the
  +//! respective backend. It is however recommended to explicitly specify the desired version instead
  +//! of using any of the `*latest*` features (see section about semantic versioning below).
  //!
  //! Note that `argmin` by default compiles with `serde` support. Therefore, unless `serde` is
  //! deliberately turned off in `argmin`, it is necessary to activiate the `serde` support in
  #![doc = concat!("argmin-math = { version = \"", env!("CARGO_PKG_VERSION"), "\", features = [\"ndarray_latest-serde\"] }")]
  //! ```
  //!
  +//! # Semantic versioning
  +//!
  +//! This crate follows semantic versioning. Adding a new backend or a new version of a backend is
  +//! not considered a breaking change. However, your code may still break if you use any of the
  +//! features containing `*latest*`. It is therefore recommended to specify the actual version of the
  +//! backend you are using.
  +//!
  //! # Contributing
  //!
  //! You found a bug? Your favourite backend is not supported? Feel free to open an issue or ideally
  