Update README for WSL UVX usage

[valdezm]

This adds WSL UVX instruction

[jssmith]

Thank you for providing these instructions. I have edited them somewhat to conform to the style of the page.

@valdezm please confirm that the changes look good to you.

[jssmith]

Thanks for the contribution! WSL instructions are definitely needed since PR #100 (now merged) only covers native uvx usage.

A few suggestions to improve this:

1. Use bash -lc instead of bash -c

Using bash -c doesn't source the user's profile, so ~/.local/bin won't be in PATH. This is why you need to hardcode the full path. Using bash -lc (login shell) would load the user's environment properly.

2. Use PyPI instead of git

PR #100 established that the PyPI package (postgres-mcp) is available and up to date. For consistency with the rest of the README, this should use uvx postgres-mcp rather than --from git+https://...@main.

3. The $WSL_USER placeholder is confusing

/home/$WSL_USER/.local/bin/uvx looks like a shell variable that would be expanded, but it's actually a placeholder for manual replacement. With the bash -lc fix above, this hardcoded path isn't needed anyway.

4. Note about pip is incorrect

"If you do not have uvx installed, you may install it using pip"

uvx comes from uv, not pip. Should link to the uv installation instructions like the rest of the README.

Suggested config

{
  "mcpServers": {
    "postgres": {
      "command": "wsl.exe",
      "args": [
        "bash",
        "-lc",
        "DATABASE_URI='postgresql://username:password@localhost:5432/dbname' uvx postgres-mcp --access-mode=unrestricted"
      ]
    }
  }
}

This:

• Uses login shell so PATH is set up correctly
• Uses PyPI package for consistency
• No hardcoded paths needed
• Inline env var is a reasonable compromise for WSL (proper env passthrough via WSLENV is more complex)

Let me know if you'd like help updating the PR!