Added standard bundle installation instructions

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | -
| Fixed tickets | #4157

Note: if you think that this draft is awful, please say it so and we'll rewrite it from scratch.
I'm not sure. The thing is that we want bundle creators to see this text "as is", without being rendered. That way they can copy-and-paste those instructions to their `README.md` files. Considering all this, I think that only the `raw` directive allow us to do this.