message: docs: specify installation for rust
  Provides a `Cargo.toml` example on how to install `fluvio` on Rust projects.
  Currently when reading documentation on an installation link points to a section that is not available. To avoid having this link, the content is replaced with the installation guide on:
diff: //! reading a previously-stored message from that same Fluvio cluster. Let's get started
  //! with a quick example where we produce and consume some messages.
  //!
  -//! # Prerequisites
  +//! # Examples
  //!
  -//! [Install Fluvio](#installation)
  +//! Fluvio's documentation provide a set of examples for Rust.
  +//! You can visit the examples page [following this link](https://www.fluvio.io/api/official/rust/examples/).
  //!
  //! # Fluvio Echo
  //!
  