Docs: four sentences still name pip after the uv migration #134

After #123, #125 and #127, four sentences in the user docs still name pip:

• installation.adoc: JPype1 "which pip installs for you", and the Python 3.15 sentence says "pip says that no version fits" (uv does not stop at the requires-python upper bound; it tries to build JPype and fails).
• which-package.adoc: the Python row says "pip refuses it, and uv tries to build JPype and fails".
• how-to/concurrency.adoc: "pip can now install the package on 3.14t".
• quickstart.adoc: "add --pre to the install line" (pip's flag; uv's is --prerelease allow).

The examples 07 to 12 still use uv venv/uv pip install inside their Docker containers; that is a larger change with its own issue.