docs: say what the installation section is before the first step (#17)

It opened with "1. Install uv" and left the shape of the thing to be inferred
from the steps: that there is no clone, no virtual environment to make, no
git, and that the package comes from the index on demand. That is the reason
somebody would pick this route, and it was the one thing the section did not
say.

The container route gets a pointer from here too, since this section is where
a reader arrives first and it is not the only way to run the server.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: BeneODev

README.md

@@ -227,6 +227,12 @@ cut access if anything looks wrong.
 
 ## Installation
 
+The simplest way to run the server — no clone, no manual virtual environment,
+no `git`. `uvx` fetches and runs it on demand from
+[PyPI](https://pypi.org/project/benethos-lexware-office-mcp/) (published as
+`benethos-lexware-office-mcp`). To run it in a container instead, see
+[In a container](#in-a-container).
+
 **1. Install uv**, if you have not already — the
 [uv installation page](https://docs.astral.sh/uv/getting-started/installation/)
 covers every platform. It brings `uvx`, and that is the only thing needed