Improve installation instructions

[DominicOram]

Currently the installation instructions are:

## Installation

Currently this relies on a branch of cs-web-lib. This is waiting on https://github.com/DiamondLightSource/cs-web-lib/pull/69#pullrequestreview-2470013371 after which the code currently in this repo will work with installation of `@diamondlightsource/cs-web-lib` but it's possible we will need to do more of this in the future if I didn't add enough there.

Clone that repository, and run

```bash
git checkout expose_hooks
npm install
npm run rollup
npm pack

and copy the generated .tgz file over to this repo

then here run npm install and also run it again on the tarball of cs-web-lib. this avoids the issue of ending up with multiple copies of react due to linked dependencies (https://react.dev/warnings/invalid-hook-call-warning#duplicate-react)

There are some issues with this:
* The referenced PR now exists and so the branch does not exist. Does this mean we no longer need to do any of these steps?
* `npm` isn't in the standard DLS path, I assume there is a module load for this? This should be documented here