docs: run quickstart script from Git Bash or WSL on Windows; fix macOS wizard note - #1887

Purpose of the change

Fix two platform-specific errors in the install docs.

Description

• docs/getting_started/quickstart.mdx: the Windows tab told users to run the
  download snippet in PowerShell, but the last line runs
  ./memmachine-compose.sh, which is a bash script and can't run there. The
  Windows tab now says to run the setup from Git Bash or a WSL terminal with
  Docker Desktop running, uses the same bash snippet as Linux/macOS, and notes
  that WSL users need Docker Desktop's WSL integration turned on. The
  "Management Scripts" section now says Windows users should run those commands
  from Git Bash or WSL too.
• docs/install_guide/configure_wizard.mdx: the macOS line said the wizard
  installs Java and Neo4j with brew. MacosInstaller doesn't call brew. It
  downloads and extracts the JDK and Neo4j tar.gz archives, the same way the
  Linux installer does. The line now says that.

Fixes/Closes

Fixes #1870

Type of change

• Documentation update

How Has This Been Tested?

• Manual verification
  • Read MacosInstaller.install_and_start_neo4j in
    packages/server/src/memmachine_server/installation/memmachine_configure.py
    and confirmed it downloads and extracts tar.gz archives. Nothing in
    installation/ calls brew.
  • Compiled both edited .mdx files with @mdx-js/mdx v3. Both parse without
    errors.

I haven't run the steps on a Windows machine.

Checklist

• I have signed the commit(s) within this pull request
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have checked my code and corrected any misspellings

Further comments

A PowerShell version of memmachine-compose.sh was the other option in the
issue. I left it out to keep this change docs-only.