Update readme recommendations for Windows

[adrianschmidt]

@dorisenthecat wrote:

Rather than "git bash" I recommend the regular Terminal in windows, with the powershell add-on poshgit.

• Git is best on the command line, install "Git for Windows" (https://gitforwindows.org/)
• Use "Windows Terminal", not cygwin, cmd, git bash emulation, etc.
• You want auto completion for Git on the command line, install power shell extension "Poshgit" (https://github.com/dahlbyk/posh-git)
• You want better Git support in VSCode, install extension "GitLens - Git SuperCharged" (https://marketplace.visualstudio.com/items?itemName=eamodio.gitlens)
• You want to use vscode for edit- and rebase (sequence) operations
  • git config --global core.editor "code --wait"
  • git config --global sequence.editor "code --wait"

Some or all of these might be nice to add to the root readme.md.