doc: add missing install instructions

[coolaj86]

There's an error when running this without uv venv. I assume it's just supposed to be run from the project directory.

This should probably also have information for how to install whichever version of python is expected to be used.

[coolaj86]

I was on a goose chase for a bit, but when I got back to this, these instructions are also not sufficient.

In my case there was also an activate step, which I didn't see the first time I used uv venv:

source ./.venv/bin/activate.fish

It's probably also best to make sure it's the correct python:

command -v python # ~/.venv/bin/python

If the uv commands are run before the uv venv is activated, they won't take full effect.

Then python ./srv/server.py (not ./server.py) will run.

It needs arguments for --host and --port to connect to an mcp client.